Thesis (Ph.D.)--Murdoch University, 2009. / Thesis submitted to the Faculty of Sustainability, Environmental and Life Sciences. Includes bibliographical references (leaves 188-208)

Memoria para optar al Título Profesional de Médico Veterinario. / En especies pelágicas como S. lalandi, se ha descrito que la flotabilidad en huevos y embriones es el reflejo de la viabilidad y calidad de estos. Esta característica, se adquiere con la proteólisis del vitelo provocando la hidratación y generando nutrientes para el desarrollo del embrión. Las enzimas involucradas en este proceso son las catepsinas, por lo que han sido propuestas como biomarcadores de calidad en estas especies. Con el objeto de conocer aspectos moleculares involucrados en la adquisición de la flotabilidad en S. lalandi, se evaluó la relación entre la expresión del mRNA que codifica para las catepsinas B, D y L y el nivel de flotabilidad de huevos y embriones tempranos de S. lalandi previamente categorizados como flotantes y no flotantes. Para esto, se colectaron muestras con distintos niveles de flotabilidad y en diferentes etapas del desarrollo. La expresión se evaluó en forma relativa mediante RT-qPCR utilizando partidores diseñados por alineamiento de secuencias de otros peces teleósteos. Los niveles de mRNA de catepsina B fueron mayores en los estadíos de huevo, mórula y blástula, sin diferencias significativas (p> 0,05) entre estadíos. En el estadío de gástrula la expresión de catepsina B disminuyó significativamente, sin presentar cambios en embriones de 24 horas. El mayor nivel de expresión de catepsina D se registró en los huevos no flotantes en comparación con los flotantes. En otros estadíos la expresión de catepsina D no presentó diferencias relacionadas con la flotabilidad de los embriones. Catepsina L, por el contrario, tuvo mayores niveles de expresión en huevos flotantes, así como también en los estadíos de gástrula y embriones de 24 horas con flotabilidad positiva. La expresión del mRNA de estas enzimas en diferentes etapas del desarrollo temprano de S. lalandi confirman su rol descrito en especies pelágicas, cumpliendo funciones específicas en la degradación de las proteínas del vitelo. Además, los perfiles de expresión observados en muestras flotantes y no flotantes permiten proponer a catepsina L como un marcador de buena calidad y a catepsina D como un marcador de mala calidad para los huevos de S. lalandi. / In pelagic species such as S. lalandi, it has been described that the buoyancy in eggs and embryos reflect their viability and quality. This feature is acquired with the yolk proteolysis, which is responsible for the hydration process and generates nutrient for the embryos. The enzymes involved in this process are the cathepsins, which have been proposed as quality biomarkers in these species. In order to know molecular aspects involved in the acquisition of buoyance in S. lalandi, the expression of cathepsin B, D and L was assessed in eggs and early embryos previously classified as floating and non- floating samples. For this, floating and non- floating samples in different developmental stages were collected. Relative expression was evaluated by RT-qPCR using primers designed from sequence alignment of others teleost fish. Cathepsin B mRNA expression levels where higher in eggs, morula and blastocyst stage, with none- statistically significant differences (p> 0,05) between these stages. In gastrula stage, the cathepsin B expression decreased significantly, without changes in 24 hours embryos. The highest expression level of cathepsin D was recorded in non-floating eggs, in comparison with those floating. In others stages, cathepsin D expression did not show differences related with the embryo buoyancy. On the contrary, cathepsin L had higher expression levels in floating eggs as well as in gastrula stage and 24 hours embryos with positive buoyancy. The enzymes mRNA expression during different early development stages in S. lalandi confirms their role described in pelagic species in the yolk protein degradation. In addition, the expression profiles observed in floating and non-floating samples allow proposing to cathepsin L as a good quality marker and cathepsin D as poor quality marker in S. lalandi eggs. / Financiamiento: Proyecto Fondecyt No. 11140639.

Memoria para optar al Título Profesional de Médico Veterinario / La flotabilidad de los embriones tempranos de peces pelágicos se asocia a la calidad y sobrevivencia de éstos. En cautiverio se ha observado una alta mortalidad embrionaria que se ha relacionado con la pérdida de flotabilidad de los huevos, proponiéndose la participación de mecanismos apoptóticos. El objetivo de este estudio fue evaluar la expresión de genes relacionados con la apoptosis celular durante el desarrollo embrionario temprano de Seriola lalandi y su relación con el nivel de flotabilidad. Para esto, se evaluó mediante RT-qPCR la expresión relativa de Bax, Caspasa-9, Caspasa-3 y Bcl-2 en cinco estadíos del desarrollo previamente clasificados como embriones flotantes y no flotantes. Se observó una mayor expresión de Bax en embriones no flotantes, la cual aumentó significativamente hasta este estadío de gástrula. Caspasa-9 presentó niveles estables de expresión en las muestras flotantes hasta gástrula. En blástulas no flotantes se presentó la mayor expresión de este gen, la cual fue estadísticamente superior a la encontrada en blástulas flotantes. En blástulas y gástrulas, Caspasa-3 presentó mayor expresión en muestras no flotantes. La mayor expresión de los factores pro-apoptóticos Bax, Caspasa-9 y Caspasa-3 en algunos embriones no flotantes de S. lalandi, permitirían relacionar la pérdida de flotabilidad de estos embriones con la participación de mecanismos de apoptosis celular. Por otro lado, la expresión de ARNm que codifica para Bcl-2 no presentó diferencias entre embriones flotantes y no flotantes, lo que sugiere la participación de este factor anti-apoptótico como protector de la viabilidad celular del embrión a través del desarrollo. / The buoyancy of the early embryos in pelagic fish is associated with it is quality and survival. High mortality of early embryos in captivity conditions has been associated with the loss of buoyancy of the eggs, where apoptotic mechanisms have been proposed. Therefore, the aim of this study was to evaluate the expression of genes related to the apoptosis process during the early embryonic development of Seriola lalandi and its relationship with the buoyancy level of the embryos. For this, the relative expression of Bax, Caspase-9, Caspase-3 and Bcl- 2 was evaluated by RT-qPCR in five development stages, previously classified as floating and non-floating ones. High Bax expression levels was observed in non-floating embryos, which increased significantly until gastrula stage. Caspase-9 showed stable expression levels in floating samples up to gastrula. In non-floating samples, the highest expression of this gene was observed at blastula stage, which was higher than floating blastulae. At both blastula and gastrula stage, Caspasa-3 showed higher expression in non-floating samples. The higher expression of the pro-apoptotic factors Bax, Caspase-9 and Caspase-3 in some non-floating embryos of S. lalandi would allow us to relate the low buoyancy of these embryos with the participation of cellular apoptosis mechanisms. On the other hand, the expression of mRNA encoding Bcl-2 does not present differences between floating and nonfloating embryos, suggesting the participation of this anti-apoptotic factor as a protector of the cellular viability of the embryo through development / Proyecto FONDECYT 11140639

Tesis presentada para optar al Grado de Magister en Ciencias de la Acuicultura / El jurel cola amarilla (Seriola lalandi) se viene cultivando en chile, durante los últimos años, y su expansión se debe a la gran demanda en el mercado internacional. El mayor conocimiento científico - técnico ha sustentado su incremento en producción, convirtiéndose en una prominente especie para el desarrollo acuícola. Dentro de las áreas de estudio en acuicultura para el aumento en producción, la nutrición ha tenido un rol relevante, que debido a los tipos de dietas, uso de antibióticos, cambia el status sanitario del pez y la composición microbiana intestinal. Estos últimos son microorganismos asociados a la microbiota normal, que otorgan beneficios como proteger al pez de ataque de patógenos y ayudar en la digestión de los ingredientes incorporados en la dieta. Sin embargo, el conocimiento de la microbiota de esta especie es muy limitada, es por eso que el objetivo de este estudio fue caracterizar la microbiota intestinal de Seriola lalandi de medio silvestre.

Japanese yellowtail Seriola quinqueradiata has been commercially farmed in Japan since the 1940s. In comparison, sea-cage farming of yellowtail kingfish Seriola lalandi in Australia is still developing, with commercial production commencing in 1998. In Australia, S. lalandi is parasitised by Zeuxapta seriolae and Benedenia seriolae. In Japan, S. quinqueradiata is parasitised by Heteraxine heterocerca and B. seriolae. These monogeneans affect industries in both countries and management of these parasites is required to prevent impacts on fish health and commercial losses. I investigated efficacy (% reduction of mean parasite abundance) for orally administered praziquantel, fenbendzole and oxfendazole against Z. seriolae and B. seriolae on S. lalandi and the efficacy of orally administered praziquantel and febantel against H. heterocerca and B. seriolae on S. quinqueradiata. Medications were administered to fish by surface coating feed pellets or via direct intubation of the stomach. Seriola lalandi administered fenbendazole and oxfendazole by surface coating of feed had lower abundance of the gill parasite Z. seriolae. Seriola quinqueradiata intubated with febantel had lower abundance of the gill parasite H. heterocerca. Neither fenbendazole nor oxfendazole administered to S. lalandi in Australia, nor febantel administered to S. quinqueradiata in Japan resulted in a lower abundance of the skin parasite B. seriolae. Praziquantel was first administered to S. lalandi by surface coating of feed. Fish rejected medicated feed, suggesting praziquantel affected its palatability. Fish treated with feed medicated with praziquantel had fewer Z. seriolae and B. seriolae than untreated fish. Praziquantel administered to S. lalandi by intubation allowed a more accurate dose to be tested without differential feeding or reduced palatability obstructing results, and resulted in fewer Z. seriolae (99.5-100 % reduction) and B. seriolae (91 – 97.7 % reduction). Intubated praziquantel also led to fewer recruitment life stages of Z. seriolae and B. seriolae, even at low doses, but did not completely eliminate them from S. lalandi. Praziquantel administered to S. lalandi alone and combined with cimetidine had high efficacy (>99%) against Z. seriolae. In comparison, praziquantel administered alone resulted in fewer B. seriolae (68.3 – 69.7 % reduction) than the same doses of praziquantel combined with cimetidine (36.9 – 40.9 % reduction). A 90.4 -100% reduction in H. heterocerca was achieved when praziquantel was administered by intubation to S. quinqueradiata in Japan but there was only a 22-77.8 % reduction in B. seriolae. The dose of PZQ (150 mg kg⁻¹ body weight day⁻¹ for 3 days) on the label of a commercially available product used to treat B. seriolae in Japanese aquaculture resulted in a 50.9% reduction against B. seriolae, but completely eliminated H. heterocerca. In trials against Z. seriolae and B. seriolae on S. lalandi in South Australia, I also screened 27 other anthelmintics and antiparasitics from the chemical groups: amprolium derivatives, benzimidazoles, benzyl ureas, diphosphate salts, imidazothiazoles, macrocyclic lactones, nitromidazoles, organophosphates, piperazines, salicylanilides, substituted phenols and tetrahydropyrimidines. Of these, only the benzimidazole, albendazole, was effective against Z. seriolae and none appeared to have an effect against B. seriolae. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1459172 / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2010

Japanese yellowtail Seriola quinqueradiata has been commercially farmed in Japan since the 1940s. In comparison, sea-cage farming of yellowtail kingfish Seriola lalandi in Australia is still developing, with commercial production commencing in 1998. In Australia, S. lalandi is parasitised by Zeuxapta seriolae and Benedenia seriolae. In Japan, S. quinqueradiata is parasitised by Heteraxine heterocerca and B. seriolae. These monogeneans affect industries in both countries and management of these parasites is required to prevent impacts on fish health and commercial losses. I investigated efficacy (% reduction of mean parasite abundance) for orally administered praziquantel, fenbendzole and oxfendazole against Z. seriolae and B. seriolae on S. lalandi and the efficacy of orally administered praziquantel and febantel against H. heterocerca and B. seriolae on S. quinqueradiata. Medications were administered to fish by surface coating feed pellets or via direct intubation of the stomach. Seriola lalandi administered fenbendazole and oxfendazole by surface coating of feed had lower abundance of the gill parasite Z. seriolae. Seriola quinqueradiata intubated with febantel had lower abundance of the gill parasite H. heterocerca. Neither fenbendazole nor oxfendazole administered to S. lalandi in Australia, nor febantel administered to S. quinqueradiata in Japan resulted in a lower abundance of the skin parasite B. seriolae. Praziquantel was first administered to S. lalandi by surface coating of feed. Fish rejected medicated feed, suggesting praziquantel affected its palatability. Fish treated with feed medicated with praziquantel had fewer Z. seriolae and B. seriolae than untreated fish. Praziquantel administered to S. lalandi by intubation allowed a more accurate dose to be tested without differential feeding or reduced palatability obstructing results, and resulted in fewer Z. seriolae (99.5-100 % reduction) and B. seriolae (91 – 97.7 % reduction). Intubated praziquantel also led to fewer recruitment life stages of Z. seriolae and B. seriolae, even at low doses, but did not completely eliminate them from S. lalandi. Praziquantel administered to S. lalandi alone and combined with cimetidine had high efficacy (>99%) against Z. seriolae. In comparison, praziquantel administered alone resulted in fewer B. seriolae (68.3 – 69.7 % reduction) than the same doses of praziquantel combined with cimetidine (36.9 – 40.9 % reduction). A 90.4 -100% reduction in H. heterocerca was achieved when praziquantel was administered by intubation to S. quinqueradiata in Japan but there was only a 22-77.8 % reduction in B. seriolae. The dose of PZQ (150 mg kg⁻¹ body weight day⁻¹ for 3 days) on the label of a commercially available product used to treat B. seriolae in Japanese aquaculture resulted in a 50.9% reduction against B. seriolae, but completely eliminated H. heterocerca. In trials against Z. seriolae and B. seriolae on S. lalandi in South Australia, I also screened 27 other anthelmintics and antiparasitics from the chemical groups: amprolium derivatives, benzimidazoles, benzyl ureas, diphosphate salts, imidazothiazoles, macrocyclic lactones, nitromidazoles, organophosphates, piperazines, salicylanilides, substituted phenols and tetrahydropyrimidines. Of these, only the benzimidazole, albendazole, was effective against Z. seriolae and none appeared to have an effect against B. seriolae. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1459172 / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2010

Thesis (PhD)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The genus Seriola includes several important commercial fish species, yet the phylogenetic relationships between species have not been fully investigated to date. This study reports the first molecular phylogeny for this genus based on two mitochondrial (Cytb and COI) and two nuclear gene (RAG1 and Rhod) fragments for all extant Seriola species (nine species, n = 27). The phylogenetic patterns resolved three main lineages: a ((S. fasciata and S. peruana), S. carpenteri) clade, a (S. dumerili and S. rivoliana) clade and a (S. lalandi and S. quinqueradiata) clade. The closure of the Tethys Sea (12 - 20 MYA) coincides with divergence of the ((S. fasciata and S. peruana), S. carpenteri) clade from the rest of the Seriola species; while the uplifting of the Isthmus of Panama (± 3 MYA) played an important role in speciation between S. fasciata and S. peruana. The climate and water temperature fluctuation in the Pliocene played important roles during the divergence of the remainder of the Seriola species. This study is also the first to describe the evolutionary history of the commercially important species Seriola lalandi across its distribution range. Global patterns of genetic variation within S. lalandi (n = 190) were examined using three genes fragments (mitochondrial DNA COI, Cytb and nuclear RAG1). Three distinct clades were identified, corresponding to three different geographic regions (North-western Pacific - Japan, North-eastern Pacific - USA, and the southern hemisphere clade). These groupings correspond with the previously identified subspecies of S. lalandi (North-western Pacific – S. lalandi aureovittata, North-eastern Pacific – S. lalandi dorsalis, and the southern hemisphere clade - S. lalandi lalandi). AMOVA results and pairwise FST values revealed significant population differentiation between these groups. The population subdivision between these clades in all probability is maintained by biogeographic or oceanographic barriers (such as the equator and East Pacific Barrier) that disrupt gene flow. The southern hemisphere clade comprised of samples from the southern Pacific (AUS, NZL and Chile) and the southern Atlantic (SA). No haplotypes were shared between these areas in the southern hemisphere. This southern hemisphere clade was further investigated with six microsatellite markers. The analyses revealed the South African populations as genetically distinct from populations of the South Pacific oceans (AMOVA, FCA and STRUCTURE results). In summary, the South African and southern Pacific grouping could be the result of recent vicariant events during the Pleistocene glacial / interglacial periods and / or contemporary oceanographic forces acting on these populations. Further population differentiation was found within the South African samples, but not in the South Pacific. In the southern Pacific clade this lack of population structure is the result of high gene flow (analysed with MIGRATE) between the sampling localities. This is the first report on the genetic structure of this commercial important species for South African populations. Five sampling localities from the west- to the east coast of South Africa were sampled (n = 201). The microsatellite analyses revealed two potentially genetically distinct groups. AMOVA, FST and FCA results suggest small but significant differentiation between populations from the west coast and from the south- and east coast, suggesting a potential genetic break in the Cape Point region (BARRIER). However, the program STRUCTURE showed a high level of admixture along the South African coast and the migration results (MIGRATE and BAYESASS) also suggest a high degree of gene flow between these regions. / AFRIKAANSE OPSOMMING: Die genus Seriola bevat verskeie kommersieel belangrike vis spesies, tog is filogenietiese verwantskap tussen species is nog nie ten volle bestudeer nie. Hierdie studie is die eeste molekulêre filogenietiese studie vir die genus gebaseer op twee mitochondriale DNA (Cytb en COI) en twee nukleêre DNA fragmente (RAG1 en Rhod) vir al die bestaande Seriola spesies (nege spesies, n = 27). Drie beranglike filogenitiese patrone is geïdentifiseer: ‘n ((S. fasciata en S. peruana), S. carpenteri) groep, ‘n (S. dumerili en S. rivoliana) groep en ‘n (S. lalandi en S. quinqueradiata) groep. Die diversifikasie van die ((S. fasciata en S. peruana), S. carpenteri) groep van die ander Seriola spesies stem oor een met die sluiting van die Tethys See (12 - 20 MYA). Terwyl die opligging van die Isthmus van Panama (± 3 MYA) ‘n belangrike rol gespeel het in die spesiasie tussen S. fasciata en S. Peruana. Die veranderlike klimaat toestande en water temperature tydens die Pliocene help met die diversifikasie van die res van die Seriola spesies. Hierdie studie is die eerste om verslag te doen op die evolusionêre geskiedenes van kommersiele belangrike vis spesies Seriola lalandi oor sy hele verspreidings gebied. Die globale patrone van genetiese variasie binne S. lalandi (n = 190) is ondersoek deur gebruik te maak van mitokondriale (Cytb en COI) en nukleêre (RAG1) DNA volgorde data. Drie groepe geassosieer met geografie is geïdentifiseer (Noord-westelike Stille Oseaan - Japan, Noord-oostelike Stille Oseaan - FSA en die suidelike hemisfeer groep). Hierdie groepeerings stem oor een met voorheen geïdentifiseerde subspesies van S. lalandi (Noord-westelike Stille Oseaan - S. lalandi aureovittata, Noord-oostelike Stille Oseaan - S. lalandi dorsalis en die suidelike hemisfeer groep - S. lalandi lalandi). AMOVA en FST resultate bevestig die hoë graad van genetiese struktuur tussen groepe. Hierdie populasie groepeerings is moonlik die oorsaak van - en onderhou deur giogeografiese and oseaanografiese grense (soos the ewenaar en EPB) wat geen vloei ontwrig. Die suidelike hemisfeer groep kan verder verdeel word in ‘n suidelike Stille Oseaan (AUS, NZL en Chile) groep en ‘n suidelike Atlantiese groep (SA). Geen haplotiepes word gedeel deur hierdie twee groepe. Hiedie suidelike hemisfeer groep was verder ondersoek met ses mikrosatelliet merkers. Die analises bevestig dat die Suid Afrikaanse populasies geneties verskillend is van die suidelike Stille Oseaan groep (AMOVA, FCA and STRUCTURE). Verdere genetiese struktuur kan verkry word binne die Suid Afrikaanse monsters, maar nie in die suidelike Stille Oseaan nie. In die suidelike Stille Oseaan hiere gebrek aan populasie struktuur is as gevolg van die hoë geen vloei (MIGRATE) tussen die lokaliteite. Hierdie is ook die eerste studie oor die genetiese structure van S. lalandi vir Suid Afrikaanse populasies. Monsters (n = 201) was geneem by vyf lokaliteite vanaf wes tot oos kus van Suid Afrika. Die mikrosatelliet analises dui op twee moontlike genetiese groepe. AMOVA, FST en FCA dui ‘n klein maar betekenisvolle differensiasie tussen populasies van die wes kus en die van die suid en oos kus. Dit dui aan op moontlike breek in die Kaap Punt omgewing (BARRIER). STRUCTURE analises toon egter ‘n bymengsel van twee groepe langs die Suid Afrikaanse kus en migrasie resultate (MIGRATE en BAYESASS) toon ook ‘n hoë graad van gene vloei tussen hierdie gebiede.

Metazoan parasites threaten the development and expansion of yellowtail kingfish (Seriola lalandi) sea-cage aquaculture in Australia. There is international speculation that parasite transmission from farmed to wild fish leads to increased incidence of parasitism in wild fish. Conversely, transfer of parasites from wild fish to farmed fish can negatively impact upon the health of farmed fish. Baseline information on the parasite assemblage of wild S. lalandi in Australia will: 1) allow informed judgments to be made in order to responsibly monitor, and perhaps remedy, potentially negative impacts and; 2) enable identification of parasite species of potential harm to the Australian S. lalandi aquaculture industry. I collected wild Seriola spp. (Carangidae) throughout southern Australia and examined them for metazoan parasites. Fifty-six metazoan parasite species are identified, including one new species. A taxonomic listing is provided for the metazoan parasites found. Taxonomic descriptions are made for the blood fluke Paradeontacylix godfreyi n. sp. (Digenea: Sanguinicolidae) and a redescription is provided for the parasitic copepod Naricolax chrysophryenus (Cyclopoida: Bomolochidae). A qualitative risk assessment was devised for the metazoan parasite taxa identified for the sea-cage aquaculture of S. lalandi in South Australia. Risk was interpreted considering the likelihood and consequence of parasite establishment and proliferation. The monogeneans Benedenia seriolae and Zeuxapta seriolae were considered extremely likely to establish and proliferate. Benedenia seriolae also poses high potential negative consequences for cost-effective S. lalandi sea-cage farming. However, the absence of potential mitigation methods and parasite management for Paradeontacylix spp. (Digenea), Kudoa sp. and Unicapsula seriolae (Myxozoa) indicates that these species may also present high negative consequences for S. lalandi aquaculture in Australia. The nature of wild Seriola migrations is critical for an understanding of the potential impact of disease and parasite interactions between wild and farmed fish. A small-scale tagging programme of wild-caught S. lalandi and S. hippos in South Australia provided insight into the movements of these species. Recapture results indicate that large S. lalandi remain in, or return to, northern Spencer Gulf. S. lalandi also move past sea-cage farms in Fitzgerald Bay, northern Spencer Gulf, which is an important consideration in view of potential expansion of the S. lalandi sea-cage industry in Spencer Gulf. There is surprisingly little experimental assessment on parasite transmission from farmed fish to wild fish. Studies assessing parasite interactions between wild and cultured fish employ models to quantify parasite population levels of cultured, wild and escaped fish, while others carry out comparative surveys of parasite prevalence and intensity over time, in areas close to and distant from farming activity. I provide preliminary data on ectoparasite prevalence and intensity on wild S. lalandi in areas close to, distant from and where there is no sea-cage farming in southern Australia. I review methods employed in the northern hemisphere to assess sea-louse transfer between wild and farmed salmon and propose methods for assessing monogenean parasite transmission from farmed to wild S. lalandi in Australia. In summary, this thesis provides insight into the potential for parasite interactions between wild and farmed S. lalandi. I document the parasite assemblage of wild and farmed S. lalandi and wild S. hippos and provide baseline data on ‘natural’ parasite prevalence and intensity. I provide a taxonomic description of a new species of blood fluke. I indicate the likelihood of parasite transfer from wild fish to farmed S. lalandi, and identify parasite taxa with potentially negative consequences for sea-cage aquaculture. I provide the first firm data that wild S. lalandi move past one area where kingfish are farmed in sea-cages in South Australia. Finally, I propose procedures to better understand the potential for monogenean parasite transmission from farmed S. lalandi to wild fish. This thesis reports new information that is important when considering and managing expansion of the S. lalandi sea-cage aquaculture industry throughout Australia. It also provides baseline data on natural parasite levels to enable ongoing monitoring of the potential impacts of the industry on wild fish populations. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1294807 / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2007

This thesis had two overriding aims. The first was to describe the biology of Samson Fish Seriola hippos and therefore extend the knowledge and understanding of the genus Seriola. The second was to uses these data to develop strategies to better manage the fishery and, if appropriate, develop catch-and-release protocols for the S. hippos sportfishery. Trends exhibited by marginal increment analysis in the opaque zones of sectioned S. hippos otoliths, together with an otolith of a recaptured calcein injected fish, demonstrated that these opaque zones represent annual features. Thus, as with some other members of the genus, the number of opaque zones in sectioned otoliths of S. hippos are appropriate for determining age and growth parameters of this species. Seriola hippos displayed similar growth trajectories to other members of the genus. Early growth in S. hippos is rapid with this species reaching minimum legal length for retention (MML) of 600mm TL within the second year of life. After the first 5 years of life growth rates of each sex differ, with females growing faster and reaching a larger size at age than males. Thus, by 10, 15 and 20 years of age, the predicted fork lengths (and weights) for females were 1088 (17 kg), 1221 (24 kg) and 1311 mm (30 kg), respectively, compared with 1035 (15 kg), 1124 (19 kg) and 1167 mm (21 kg), respectively for males. Despite these differences, female and male S. hippos attained similar maximum age, i.e. 29 (1470 mm FL) and 28 years (1280 mm FL), respectively. The maximum age determined for S. hippos is greater than that recorded for any other Seriola spp. The largest female and male S. hippos recorded during this study were encountered during the tagging component and had fork lengths of 1600 mm and 1380 mm, respectively. Seriola hippos has a protracted spawning period, ca four months, which starts in late spring and continues through summer into early autumn during which time many individuals engage in large spawning aggregations on the lower west coast of Australia. The length at which 50 % of the females in the population reached maturity was 831 mm FL (888 mm TL) and approximately 4 years of age, whilst all females over 950 mm FL were mature. Whilst aggregated for spawning S. hippos ceases feeding, however, during the non-spawning period this species can best be described as an opportunistic carnivore which feeds on a variety of pelagic and demersal prey. This study has greatly increased our understanding of S. hippos movement on the west and south coasts of Australia and has documented, for the first time, the migratory behaviour of a carangid in these waters. Many S. hippos individuals undertake long distance migrations to join spawning aggregation sites near Rottnest Island. Individuals tagged at these aggregation sites where recaptured throughout this species distribution along the south coast of Australia, some after travelling distances of over 2400 km. Many S. hippos individuals displayed strong temporal and spatial spawning ground fidelity as numerous fish released at the spawning aggregations were recaptured at the exact same spawning site at similar times in subsequent years. Tagging data suggest that on the completion of spawning S. hippos individuals return to a resident location and remain in that general vicinity over the winter months. This study has developed a hypothesis describing larval dispersal associated with the S. hippos spawning behaviour exhibited near Rottnest Island. It is proposed that variations in the prevailing ocean currents, at this important spawning location throughout the protracted spawning period, leads to high intra and inter-annual variation in larval distribution and survival. The affect of this variation on the evolution of the spawning and migratory behaviour displayed by S. hippos is discussed. A recent increase in the popularity of S. hippos as a catch-and-release sportfish has led to concerns by some anglers about post release survival of this species, particularly due to the depth of capture. Short term mortality of S. hippos capture at the sportfishing sites was assessed by monitoring fish held within an enclosure near the site of capture for up to 31 hours post release. The total hooking mortality of S. hippos subjected to catch-and-release angling within the Rottnest Island sportfishery is approximately 8%. Most of this observed mortality is delayed and occurs sometime after release. Although best handling practises require ongoing development, the current level of mortality associated with this catch-and-release fishery is considered acceptable. Furthermore, this mortality is likely to have little effect on the S. hippos population due to the high abundance of this species and the fact that even the highest fishing effort yields a relatively low catch. Seriola hippos exhibits a typical teleost neuroendocrine stress response associated with catch-and-release. The physiological dysfunction associated with the stress of capture in this species does not appear to cause any post release mortality. Instead, most mortality was attributable to barotrauma, however, although mortality in S. hippos increases with capture depth, this species is much less susceptible to depth induced mortality than other commonly targeted species in which barotrauma has been observed. This study developed key handling protocols for fishers who catch-and-release S. hippos at the Rottnest Island aggregation sites. These protocols cover aspects of catch-and-release fishing such as hook type, water depth, time at surface, release method and shark predation. Almost all S. hippos observed during capture from deep water released large quantities of gas from the opercular region, particularly during the last 10 to 20 m before reaching the surface. This phenomenon has also been witnessed by divers and fishers to occur under natural conditions. Investigations into this release of gas revealed this physoclistous species to exhibit unique swim bladder characteristics. Seriola hippos possess a membranous tube that connects the posterior-dorsal surface of the swim bladder internally to a region under each operculum externally. This connection, termed the swim bladder vent, allows the escape of expanding swim bladder gases on rapid ascent. The presence of the swim bladder vent provides an explanation as to why the incidence of external barotrauma symptoms in S. hippos captured from the deepwater was low. The ability to expel excess swim bladder gases during rapid ascent whilst retaining full swim bladder function is likely to offer this semi-pelagic species considerable advantages when hunting prey, avoiding predators and engaging in spawning activities. Preliminary estimates of total mortality indicated that S. hippos is not currently subjected to a high level of fishing pressure. However, managers must remain mindful of the fact that the size at which females reach sexual maturity, i.e. 888 mm TL, is greater than the current minimum legal length, i.e. 600 mm, and thus fishers are currently allowed to harvest sexually immature fish. Furthermore, the effectiveness of future conservation measures must consider the large scale migration and spawning strategy undertaken by this species in order to ensure its protection. The collaborative research approach undertaken during this study demonstrated that a high level of community engagement produced a large amount of research interest, increased stakeholder satisfaction from project input, improved understanding of research outcomes, and increased research uptake, all of which has led to increased stewardship and conservation of the S. hippos fishery and fisheries resources in general. Indeed, projects of this nature would not be possible without this type of approach.

Metazoan parasites threaten the development and expansion of yellowtail kingfish (Seriola lalandi) sea-cage aquaculture in Australia. There is international speculation that parasite transmission from farmed to wild fish leads to increased incidence of parasitism in wild fish. Conversely, transfer of parasites from wild fish to farmed fish can negatively impact upon the health of farmed fish. Baseline information on the parasite assemblage of wild S. lalandi in Australia will: 1) allow informed judgments to be made in order to responsibly monitor, and perhaps remedy, potentially negative impacts and; 2) enable identification of parasite species of potential harm to the Australian S. lalandi aquaculture industry. I collected wild Seriola spp. (Carangidae) throughout southern Australia and examined them for metazoan parasites. Fifty-six metazoan parasite species are identified, including one new species. A taxonomic listing is provided for the metazoan parasites found. Taxonomic descriptions are made for the blood fluke Paradeontacylix godfreyi n. sp. (Digenea: Sanguinicolidae) and a redescription is provided for the parasitic copepod Naricolax chrysophryenus (Cyclopoida: Bomolochidae). A qualitative risk assessment was devised for the metazoan parasite taxa identified for the sea-cage aquaculture of S. lalandi in South Australia. Risk was interpreted considering the likelihood and consequence of parasite establishment and proliferation. The monogeneans Benedenia seriolae and Zeuxapta seriolae were considered extremely likely to establish and proliferate. Benedenia seriolae also poses high potential negative consequences for cost-effective S. lalandi sea-cage farming. However, the absence of potential mitigation methods and parasite management for Paradeontacylix spp. (Digenea), Kudoa sp. and Unicapsula seriolae (Myxozoa) indicates that these species may also present high negative consequences for S. lalandi aquaculture in Australia. The nature of wild Seriola migrations is critical for an understanding of the potential impact of disease and parasite interactions between wild and farmed fish. A small-scale tagging programme of wild-caught S. lalandi and S. hippos in South Australia provided insight into the movements of these species. Recapture results indicate that large S. lalandi remain in, or return to, northern Spencer Gulf. S. lalandi also move past sea-cage farms in Fitzgerald Bay, northern Spencer Gulf, which is an important consideration in view of potential expansion of the S. lalandi sea-cage industry in Spencer Gulf. There is surprisingly little experimental assessment on parasite transmission from farmed fish to wild fish. Studies assessing parasite interactions between wild and cultured fish employ models to quantify parasite population levels of cultured, wild and escaped fish, while others carry out comparative surveys of parasite prevalence and intensity over time, in areas close to and distant from farming activity. I provide preliminary data on ectoparasite prevalence and intensity on wild S. lalandi in areas close to, distant from and where there is no sea-cage farming in southern Australia. I review methods employed in the northern hemisphere to assess sea-louse transfer between wild and farmed salmon and propose methods for assessing monogenean parasite transmission from farmed to wild S. lalandi in Australia. In summary, this thesis provides insight into the potential for parasite interactions between wild and farmed S. lalandi. I document the parasite assemblage of wild and farmed S. lalandi and wild S. hippos and provide baseline data on ‘natural’ parasite prevalence and intensity. I provide a taxonomic description of a new species of blood fluke. I indicate the likelihood of parasite transfer from wild fish to farmed S. lalandi, and identify parasite taxa with potentially negative consequences for sea-cage aquaculture. I provide the first firm data that wild S. lalandi move past one area where kingfish are farmed in sea-cages in South Australia. Finally, I propose procedures to better understand the potential for monogenean parasite transmission from farmed S. lalandi to wild fish. This thesis reports new information that is important when considering and managing expansion of the S. lalandi sea-cage aquaculture industry throughout Australia. It also provides baseline data on natural parasite levels to enable ongoing monitoring of the potential impacts of the industry on wild fish populations. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1294807 / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2007