Catch rates of target and non-target species from commercial shrimp and reef fish fisheries operating in the U.S. southeastern region and associated fishing practices are provided in relation to an environmentally sound and economically driven approach to resource conservation. Beginning in 1992, fishery observers were placed aboard commercial vessels in the southeastern shrimp fishery. From 1993 through 1995 the program expanded to include reef fish vessels in the Gulf of Mexico (Gulf), and during 2004 and 2005 skimmer trawl vessels in coastal Louisiana. Data from 27,868 tows were collected aboard shrimp vessels. Total catch rates in kilograms per hour were 30.8 in the Gulf, and 27.7 in the southeastern Atlantic. In the Gulf, finfish comprised 65% of the total weight, with penaeid shrimp at 16%, nonpenaeid shrimp crustaceans at 13%, non-crustacean invertebrates at 4%, and debris at 1%. In the southeastern Atlantic, finfish accounted for 47%, with penaeid shrimp at 24%, invertebrates at 18%, crustaceans at 8%, and debris at 3%. In the Gulf, finfish catch rates by weight were significantly higher in Alabama/Mississippi and Louisiana as compared with Texas and Florida. Shrimp catchper- unit-effort (CPUE) was significantly higher off Texas. For all states areas, higher shrimp catch rates occurred in nearshore waters. Red snapper (Lutjanus campechanus) CPUE was significantly higher off Texas in offshore waters during September through December. Assessment of the directed commercial reef fish fishery revealed relatively low release mortality. Based on surface release observations of under-sized target and unwanted species, the majority of fish were released alive with release mortality ranging from approximately 2% to 5% for all gear types. Five hundred forty-eight sea turtle captures were documented aboard commercial shrimp vessels from 1992 through 2005. Ratio estimation reflected higher catch rates in nets not equipped with turtle excluder devices (TEDs). Two alternative methods, logistic regression and conceptual modeling, revealed reduced take levels in TEDequipped nets. Data from 307 tows were collected aboard skimmer trawl vessels. Penaeid shrimp accounted for 66% of the total catch, followed by finfish at 19%, crustaceans at 7%, discarded penaeid shrimp at 6%, and debris at 3%.

Orientador: Rogerio Caetano Costa / Resumo: Os objetivos deste estudo foram: 1) investigar a composição taxonômica de Brachyura; 2) avaliar a assembleia destes por meio dos índices ecológicos; 3) verificar a relação das espécies em função dos fatores abióticos; e 4) analisar se há sincronismo entre os períodos reprodutivos das espécies mais abundantes em comparação ao camarão alvo da pesca X. kroyeri. Foram realizadas coletas mensais (julho/12 a junho/14) na região marinha (4 estações amostrais: E1, E2, E3 e E4) e na região de Mar Pequeno (MP) (3 estações amostrais: E5, E6, e E7), com um barco camaroeiro equipado com redes “double rig”. Foram calculados o índice de Shannon (H), a equidade (J’) a Riqueza (S) e o Índice de Valor Ecológico (IVE), e avaliou-se as relações entre espécies X estações amostradas e entre regiões X períodos (análise de cluster). A temperatura variou entre as estações do ano (maior no verão e menor no inverno), mas não variou entre as regiões amostradas. Já a salinidade variou entre as regiões, sendo menor no MP. O sedimento foi composto pela mistura de areia fina e muito fina. O teor de matéria orgânica foi similar entre as estações de coleta, com exceção de E4 e E5. A concentração média de clorofila variou entre as estações do ano, sendo maior no verão e menor no inverno. Um total de 19.501 indivíduos de Brachyura foi coletado, representados por 25 espécies, 18 gêneros e 13 famílias, sendo elas: Portunidae, Aethridae, Leucosiidae, Epialtidae, Menippidae, Pinnotheridae, Inachoididae, Dromiidae, ... (Resumo completo, clicar acesso eletrônico abaixo) / Doutor

Made available in DSpace on 2014-06-12T22:58:01Z (GMT). No. of bitstreams: 2 arquivo1443_1.pdf: 3633149 bytes, checksum: 40243e6f486c59abff57d572e11594dd (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2009 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Pomacanthus paru tem grande importância para o aquarismo brasileiro, além de ser a segunda espécie marinha mais exportada desde 2000. Os objetivos desta pesquisa foram os seguintes: (a) descrever a biologia reprodutiva e determinar a idade e o crescimento de P. paru, (b) analisar a diversidade genética de P. paru e P. arcuatus a partir do DNA mitocondrial, (c) registrar as espécies de peixes ornamentais capturadas como bycatch através da pesca com armadilhas e propor uma metodologia para determinar a sustentabilidade de captura das principais espécies ornamentais marinhas no Brasil. Amostragens semanais foram realizadas durante o período de março 2006 a fevereiro 2007. Os exemplares menores de 15 cm foram comprados de coletores de peixes ornamentais. Os peixes foram medidos, pesados, e as gônadas e os otólitos foram removidos. Amostras de músculo e do fígado foram armazenadas para o estudo genético. A região 16S rDNA foi amplificada e sequências do ADN mitocondrial foram utilizadas para a análise dos haplótipos. Para a proposição da metodologia de sustentabilidade de captura, cada espécie foi avaliada segundo dois grupos de critérios: (1) vulnerabilidade relativa à captura pelas armadilhas; (2) resiliência da população relacionada à mortalidade devido à pressão pesqueira. No total, 236 indivíduos foram analisados, sendo 139 fêmeas, 86 machos e 11 que não tiveram o sexo definido. P. paru é uma espécie gonocorística, que se reproduz ao longo do ano, com as fêmeas apresentando dois picos de desova (Fevereiro-Março/Setembro-Outubro). As fêmeas foram mais abundantes em todos os meses, exceto em outubro. O L50 é atingido aos 30 cm para as fêmeas e 35 cm para os machos. A idade dos indivíduos amostrados de P. paru variou de 1 a 27 anos. P. paru atinge o comprimento máximo lentamente e tem um longo ciclo de vida. Para P. paru seis haplótipos foram encontrados, enquanto em P. arcuatus apenas um, incluindo os espécimes do Caribe. Foram registradas como bycatch, 19 espécies pertencentes a 10 famílias. As espécies cujas capturas foram menos sustentáveis foram Holacanthus tricolor, H. ciliaris, Chaetodon striatus e P. paru. O manejo de P. paru deve incluir medidas baseadas no tamanho de primeira maturação sexual, bem como nos parâmetros de crescimento aqui estabelecidos. Os resultados relacionados à genética representam um primeiro passo para se compreender as estruturas populacionais de espécies tão próximas filogenética e ecologicamente como P. paru e P. arcuatus. A nova metodologia aqui proposta deverá ser uma ferramenta útil e alternativa para o manejo e avaliação da sustentabilidade de captura das espécies oriundas de pescarias multi-específicas, com poucos dados disponíveis e que ocorrem em áreas de alta riqueza, como os recifes

The pelagic stingray, Pteroplatytrygon violacea, is a bycatch species in the global pelagic longline fishery. However, little research has been conducted on its basic biology, including prey composition, trophic positioning, and habitat utilization. Descriptions of the habitat utilization have largely been through indirect analyses of catch rates in commercial fisheries, which also provided no information on actual behaviors. The first chapter of this thesis will describe the habitat utilization and behavior of four individual pelagic stingrays using electronic tagging technology. Prior diet descriptions were hampered, in part, by low sample sizes and accordingly provided little information on the ecological interactions of these animals. Similarly, the second chapter of this thesis will therefore provide a new diet description for the pelagic stingray using a combined analysis of traditional stomach contents with stable isotope values, thereby addressing both ingestion and assimilation. A more robust study of the trophic dynamics of the pelagic stingray, in conjunction with the description of its habitat utilization, will provide a better understanding of its role within the pelagic ecosystem. Ultimately, the goal is to obtain knowledge of the less economic species with good science so when management approaches shift from species-specific to ecosystem based, the transition will already have known information to change efficiently.

Magister Scientiae (Biodiversity and Conservation Biology) - MSc (Biodiv and Cons Biol) / Squalus acutipinnis and S. bassi may be the most common dogfish species around South Africa, and show overlap in their latitudinal and bathymetric distributions. Even though these sharks are likely endemics, they are also the common bycatch species and still, species-specific studies are lacking. The overall objective of this thesis was to understand the intraspecific and interspecific variability in the distribution and feeding ecology of these two species around the West and South coasts of South Africa. All species catch records and samples were collected during routine demersal hake biomass research surveys, conducted by the Department of Forestry Fisheries and the Environment (DFFE). Distributional patterns were evaluated using catch records, dating from 1984 to 2015. These results indicated that S. acutipinnis were commonly caught on the South coast whereas S. bassi was more abundant on the West coast.

Orientador: Wagner Cotroni Valenti / Resumo: Nos últimos anos, a fauna acompanhante da pesca camaroeira vem sendo alvo de estudos por ser um dos fatores do grande impacto ambiental causado pela pesca de arrasto. Em contrapartida, esse rejeito de pesca pode ter propriedades funcionais e bioativas, como peptídeos antioxidantes, que poderiam agregar valor a esse rejeito e se tornar um produto de interesse para as indústrias alimentícias. Assim, o presente estudo visou investigar a atividade antioxidante dos hidrolisados proteicos obtidos dos animais mais abundantes da fauna acompanhante e microencapsular esses hidrolisados para agregar valor à este material normalmente descartado. Os resultados demonstram que a hidrólise enzimática, utilizando as enzimas comerciais Alcalase 2.4 L® e Protamex®, é um método eficiente para liberar peptídeos de interesse econômico nas duas espécies mais abundantes de peixes (Micropogonias furnieri e Paralonchurus brasilensis) e nas duas mais abundantes de crustáceos (Callinectes ornatus e Hepatus pudibundus). A hidrólise liberou peptídeos com atividade antioxidante em todas as amostras analisadas, submetidas às duas enzimas testadas. A coacervação complexa e subsequente microencapsulação por spray-drying mostrou-se eficiente para proteger a atividade antioxidante desses hidrolisados proteicos. Assim, os resultados fornecem evidências para o potencial uso dos hidrolisados das espécies analisadas como ingrediente funcional ou nutracêutico na indústria alimentícia. / Abstract: In recent years, the bycatch of shrimp fishing has been the subject of studies as it is one of the factors of the great environmental impact caused by trawling. However, this bycatch can have functional and bioactive properties, such as antioxidant peptides, which could add value to this reject and become a product of interest to the food industries. Thus, the present study aimed to investigate the antioxidant activity of protein hydrolysates obtained from the most abundant animals of the bycatch and to microencapsulate these hydrolysates to add value to this normally discarded material. The results demonstrate that enzymatic hydrolysis, using the commercial enzymes Alcalase 2.4 L® and Protamex®, is an efficient method to release peptides of economic interest in the two most abundant species of fish (Micropogonias furnieri and Paralonchurus brasilensis) and in the two most abundant crustaceans (Callinectes ornatus and Hepatus pudibundus). Hydrolysis released peptides with antioxidant activity in all samples analyzed, submitted to the two enzymes tested. Complex coacervation and subsequent microencapsulation by spray-drying proved to be efficient to protect the antioxidant activity of these protein hydrolysates. Thus, the results provide evidence for the potential use of hydrolysates of the analyzed species as a functional or nutraceutical ingredient in the food industry. / Doutor

The chondrichthyan (shark, batoid and holocephalan) bycatch of the Queensland East Coast Trawl Fishery (ECTF) was examined through a series of fishery-independent trawl surveys, together with fishery-dependent (opportunistic) sampling. Project aims were to document the chondrichthyan bycatch composition in order to test the effectiveness of turtle exclusion devices (TEDs) and bycatch reduction devices (BRDs), to examine biological aspects of bycatch species, and to combine data collected through these parts to assess the conservation status and sustainability of bycatch species. A total of 37 chondrichthyan species (one holocephalan, 19 batoids and 17 sharks) from 18 families were recorded in the bycatch of the fishery. The most speciose families recorded were the stingrays (Dasyatidae; 7 species), the requiem sharks (Carcharhinidae; 5 species), the catsharks (Scyliorhinidae; 4 species) and the stingarees (Urolophidae; 3 species). Chondrichthyan bycatch was highly variable between fishery sectors; catch rates were low in the tiger/Endeavour prawn sector (north Queensland; 0.02–0.12 individuals ha-1 trawled) and in the eastern king prawn (deepwater) sector (southern Queensland; 0.08 individuals ha-1 trawled), intermediate in Hervey Bay (southern Queensland; 0.25 individuals ha-1 trawled) and in the scallop sector (central Queensland coast; 0.31 individuals ha-1 trawled) and highest in the eastern king prawn (shallow water) sector (southern Queensland; 0.96 individuals ha-1 trawled). Chondrichthyan bycatch in the eastern king prawn (shallow water) sector was dominated by the three batoids Aptychotrema rostrata, Trygonoptera testacea and Urolophus kapalensis (~92% of the chondrichthyan bycatch by number), in the eastern king prawn (deepwater) sector by the skate Dipturus polyommata and the two catsharks Asymbolus rubiginosus and Figaro boardmani (~83% of the chondrichthyan bycatch by number), in the scallop sector by the three batoids A. rostrata, Neotrygon kuhlii and Neotrygon picta (~91% of the chondrichthyan bycatch by number), and in the tiger/Endeavour prawn sector by the two batoids Himantura astra and Gymnura australis and the two sharks Chiloscyllium punctatum and Hemigaleus australiensis (~67% of the chondrichthyan bycatch by number). The testing of TEDs and BRDs, which are mandatory throughout the fishery, demonstrated only a limited ability to reduce chondrichthyan bycatch in the ECTF, which is comprised mainly of relatively small species. The shorter trawl durations of the surveys compared with normal commercial activities may have under-represented larger species. No significant reductions in chondrichthyan bycatch were found using a TED and a radial escape section BRD in the eastern king prawn (shallow water) sector, using a TED and a square-mesh codend BRD in the eastern king prawn (deepwater) sector, or using a TED and a fisheye BRD in Hervey Bay. There was however, a significant difference in the probability of capturing the group ‘sharks and guitarfishes’ (comprised largely of A. rostrata) between codend types in the scallop sector, with the lowest probability of capture in nets fitted with both a TED and a square-mesh codend BRD (the difference was largely attributed to the effects of the TED). In the tiger/Endeavour prawn sector, in which three different BRDs were trialed (fisheye, square-mesh codend, square-mesh panel), the probability of capturing chondrichthyans was significantly lower in nets fitted with a fisheye BRD than in the standard (control) net, and the probability of capturing batoids was significantly lower in nets fitted with a fisheye BRD or with a square-mesh codend BRD than in the standard (control) net. The small sample size of chondrichthyan catches in some sectors may have reduced to power to detect bycatch reduction. The biology of several bycatch species from the families Rajidae, Rhinobatidae, Urolophidae and Scyliorhinidae was examined. For D. polyommata, size at birth was estimated at ~100–110 mm total length (LT), size at first feeding at ~105–110mm LT, size at 50% maturity (LT50 and 95% CI) at 321 (305–332) mm LT for females and 300 (285–306) mm LT for males. Diet (described by the index of relative importance as a percentage) was predominantly crustacean based, with carid shrimps (53.6%) and penaeoid prawns (23.3%) being the most significant prey groups. For A. rostrata, size at birth was estimated at <170 mm LT, size at 50% maturity (LT50 and 95% CI) at 640 (618–663) mm LT for females and 597 (551–649) mm LT for males, and litter size was 9–20 (n = 9; mean ± S.E. = 15.1 ± 1.2). For T. testacea, size at birth was estimated at 77–100 mm disc width (WD), size at 50% maturity (WD50 and 95% CI) at 163 (156–169) mm WD for females and 146 (140–150) mm WD for males, and litter size was always one (n = 6). For U. kapalensis, size at birth was estimated at 75–100 mm WD, size at 50% maturity (WD50 and 95% CI) at 154 (145–160) mm WD for females and 155 (149–159) mm WD for males, and litter size was always one (n = 16). The catsharks A. analis, A. rubiginosus and F. boardmani were all confirmed as single oviparous species (carrying only one egg case in each uterus at one time). Ovarian fecundity (the number of vitellogenic follicles) averaged 13.6 (range 13–20) in A. analis, 13.5 (range 5–23) in A. rubiginosus and 10.4 (range 9–13) in F. boardmani. While only limited data were available from southern Queensland, several indicators suggest that Asymbolus catsharks are reproductively active year-round. A general lack of small-sized or immature catsharks captured during the study made assessments of size at maturity difficult for these species. The conservation status of ECTF bycatch species was examined through the application of the IUCN Red List of Threatened SpeciesTM Categories and Criteria, which considers extinction risk at the global level. Of the 24 ECTF chondrichthyan bycatch species evaluated against the IUCN Red List Categories and Criteria, four have been assessed globally as Vulnerable (a threatened category indicating that a species is ‘facing a high risk of extinction in the wild’), seven as Near Threatened, 11 as Least Concern and two as Data Deficient. While the four globally threatened species (A. nichofii, Heteroscyllium colcloughi, Rhynchobatus australiae and Urolophus sufflavus) were only minor components of the ECTF bycatch, their global conservation status warrants that fisheries management and industry should act to ensure minimal impacts on these species. An ecological risk assessment method (Susceptibility-Recovery Analysis) was used to assess the relative sustainability or risk of individual species to the fishing activities of the ECTF. Two separate approaches were taken to the technique, which considers sustainability to be dependent on the susceptibility of a species to the fishery and the recovery potential of a species after depletion by fishing activities. The first approach applied the precautionary principal when data were lacking for the calculation of recovery attributes, while the second used biological data from similar species when species-specific data were lacking. The precautionary approach tended to overestimate risk to poorly known oviparous species. The biological approach suggested that A. nichofii, F. boardmani, Rhizoprionodon acutus, Rhizoprionodon taylori and Rhynchobatus palpebratus face the least risk (i.e. were the most sustainable) while several medium-large batoids and the sharks Loxodon macrorhinus and Heteroscyllium colcloughi were the species most at risk (i.e. least sustainable). Demonstrating ecological sustainability of the ECTF will need to be a continued management objective into the future. To further improve the ecological sustainability of the fishery in relation to sharks, batoids and holocephalans, a number of management recommendations are proposed: (1) give warranted conservation consideration to listed threatened species as well as species identified as being at risk; (2) expand required logbook information on chondrichthyan species to include recording of catches of these species; (3) encourage safe release practices for all chondrichthyans to maximise survivorship of discards; (4) initiate research into the survivorship of discards; (5) ensure long-term observer coverage on commercial vessels to monitor bycatch levels; and, (6) test and quantify reduced TED bar spacings (presently 120 mm) in fishery sectors which show the highest chondrichthyan bycatch levels, that is, the eastern king prawn (shallow water) and scallop sectors.

The chondrichthyan (shark, batoid and holocephalan) bycatch of the Queensland East Coast Trawl Fishery (ECTF) was examined through a series of fishery-independent trawl surveys, together with fishery-dependent (opportunistic) sampling. Project aims were to document the chondrichthyan bycatch composition in order to test the effectiveness of turtle exclusion devices (TEDs) and bycatch reduction devices (BRDs), to examine biological aspects of bycatch species, and to combine data collected through these parts to assess the conservation status and sustainability of bycatch species. A total of 37 chondrichthyan species (one holocephalan, 19 batoids and 17 sharks) from 18 families were recorded in the bycatch of the fishery. The most speciose families recorded were the stingrays (Dasyatidae; 7 species), the requiem sharks (Carcharhinidae; 5 species), the catsharks (Scyliorhinidae; 4 species) and the stingarees (Urolophidae; 3 species). Chondrichthyan bycatch was highly variable between fishery sectors; catch rates were low in the tiger/Endeavour prawn sector (north Queensland; 0.02–0.12 individuals ha-1 trawled) and in the eastern king prawn (deepwater) sector (southern Queensland; 0.08 individuals ha-1 trawled), intermediate in Hervey Bay (southern Queensland; 0.25 individuals ha-1 trawled) and in the scallop sector (central Queensland coast; 0.31 individuals ha-1 trawled) and highest in the eastern king prawn (shallow water) sector (southern Queensland; 0.96 individuals ha-1 trawled). Chondrichthyan bycatch in the eastern king prawn (shallow water) sector was dominated by the three batoids Aptychotrema rostrata, Trygonoptera testacea and Urolophus kapalensis (~92% of the chondrichthyan bycatch by number), in the eastern king prawn (deepwater) sector by the skate Dipturus polyommata and the two catsharks Asymbolus rubiginosus and Figaro boardmani (~83% of the chondrichthyan bycatch by number), in the scallop sector by the three batoids A. rostrata, Neotrygon kuhlii and Neotrygon picta (~91% of the chondrichthyan bycatch by number), and in the tiger/Endeavour prawn sector by the two batoids Himantura astra and Gymnura australis and the two sharks Chiloscyllium punctatum and Hemigaleus australiensis (~67% of the chondrichthyan bycatch by number). The testing of TEDs and BRDs, which are mandatory throughout the fishery, demonstrated only a limited ability to reduce chondrichthyan bycatch in the ECTF, which is comprised mainly of relatively small species. The shorter trawl durations of the surveys compared with normal commercial activities may have under-represented larger species. No significant reductions in chondrichthyan bycatch were found using a TED and a radial escape section BRD in the eastern king prawn (shallow water) sector, using a TED and a square-mesh codend BRD in the eastern king prawn (deepwater) sector, or using a TED and a fisheye BRD in Hervey Bay. There was however, a significant difference in the probability of capturing the group ‘sharks and guitarfishes’ (comprised largely of A. rostrata) between codend types in the scallop sector, with the lowest probability of capture in nets fitted with both a TED and a square-mesh codend BRD (the difference was largely attributed to the effects of the TED). In the tiger/Endeavour prawn sector, in which three different BRDs were trialed (fisheye, square-mesh codend, square-mesh panel), the probability of capturing chondrichthyans was significantly lower in nets fitted with a fisheye BRD than in the standard (control) net, and the probability of capturing batoids was significantly lower in nets fitted with a fisheye BRD or with a square-mesh codend BRD than in the standard (control) net. The small sample size of chondrichthyan catches in some sectors may have reduced to power to detect bycatch reduction. The biology of several bycatch species from the families Rajidae, Rhinobatidae, Urolophidae and Scyliorhinidae was examined. For D. polyommata, size at birth was estimated at ~100–110 mm total length (LT), size at first feeding at ~105–110mm LT, size at 50% maturity (LT50 and 95% CI) at 321 (305–332) mm LT for females and 300 (285–306) mm LT for males. Diet (described by the index of relative importance as a percentage) was predominantly crustacean based, with carid shrimps (53.6%) and penaeoid prawns (23.3%) being the most significant prey groups. For A. rostrata, size at birth was estimated at <170 mm LT, size at 50% maturity (LT50 and 95% CI) at 640 (618–663) mm LT for females and 597 (551–649) mm LT for males, and litter size was 9–20 (n = 9; mean ± S.E. = 15.1 ± 1.2). For T. testacea, size at birth was estimated at 77–100 mm disc width (WD), size at 50% maturity (WD50 and 95% CI) at 163 (156–169) mm WD for females and 146 (140–150) mm WD for males, and litter size was always one (n = 6). For U. kapalensis, size at birth was estimated at 75–100 mm WD, size at 50% maturity (WD50 and 95% CI) at 154 (145–160) mm WD for females and 155 (149–159) mm WD for males, and litter size was always one (n = 16). The catsharks A. analis, A. rubiginosus and F. boardmani were all confirmed as single oviparous species (carrying only one egg case in each uterus at one time). Ovarian fecundity (the number of vitellogenic follicles) averaged 13.6 (range 13–20) in A. analis, 13.5 (range 5–23) in A. rubiginosus and 10.4 (range 9–13) in F. boardmani. While only limited data were available from southern Queensland, several indicators suggest that Asymbolus catsharks are reproductively active year-round. A general lack of small-sized or immature catsharks captured during the study made assessments of size at maturity difficult for these species. The conservation status of ECTF bycatch species was examined through the application of the IUCN Red List of Threatened SpeciesTM Categories and Criteria, which considers extinction risk at the global level. Of the 24 ECTF chondrichthyan bycatch species evaluated against the IUCN Red List Categories and Criteria, four have been assessed globally as Vulnerable (a threatened category indicating that a species is ‘facing a high risk of extinction in the wild’), seven as Near Threatened, 11 as Least Concern and two as Data Deficient. While the four globally threatened species (A. nichofii, Heteroscyllium colcloughi, Rhynchobatus australiae and Urolophus sufflavus) were only minor components of the ECTF bycatch, their global conservation status warrants that fisheries management and industry should act to ensure minimal impacts on these species. An ecological risk assessment method (Susceptibility-Recovery Analysis) was used to assess the relative sustainability or risk of individual species to the fishing activities of the ECTF. Two separate approaches were taken to the technique, which considers sustainability to be dependent on the susceptibility of a species to the fishery and the recovery potential of a species after depletion by fishing activities. The first approach applied the precautionary principal when data were lacking for the calculation of recovery attributes, while the second used biological data from similar species when species-specific data were lacking. The precautionary approach tended to overestimate risk to poorly known oviparous species. The biological approach suggested that A. nichofii, F. boardmani, Rhizoprionodon acutus, Rhizoprionodon taylori and Rhynchobatus palpebratus face the least risk (i.e. were the most sustainable) while several medium-large batoids and the sharks Loxodon macrorhinus and Heteroscyllium colcloughi were the species most at risk (i.e. least sustainable). Demonstrating ecological sustainability of the ECTF will need to be a continued management objective into the future. To further improve the ecological sustainability of the fishery in relation to sharks, batoids and holocephalans, a number of management recommendations are proposed: (1) give warranted conservation consideration to listed threatened species as well as species identified as being at risk; (2) expand required logbook information on chondrichthyan species to include recording of catches of these species; (3) encourage safe release practices for all chondrichthyans to maximise survivorship of discards; (4) initiate research into the survivorship of discards; (5) ensure long-term observer coverage on commercial vessels to monitor bycatch levels; and, (6) test and quantify reduced TED bar spacings (presently 120 mm) in fishery sectors which show the highest chondrichthyan bycatch levels, that is, the eastern king prawn (shallow water) and scallop sectors.

The chondrichthyan (shark, batoid and holocephalan) bycatch of the Queensland East Coast Trawl Fishery (ECTF) was examined through a series of fishery-independent trawl surveys, together with fishery-dependent (opportunistic) sampling. Project aims were to document the chondrichthyan bycatch composition in order to test the effectiveness of turtle exclusion devices (TEDs) and bycatch reduction devices (BRDs), to examine biological aspects of bycatch species, and to combine data collected through these parts to assess the conservation status and sustainability of bycatch species. A total of 37 chondrichthyan species (one holocephalan, 19 batoids and 17 sharks) from 18 families were recorded in the bycatch of the fishery. The most speciose families recorded were the stingrays (Dasyatidae; 7 species), the requiem sharks (Carcharhinidae; 5 species), the catsharks (Scyliorhinidae; 4 species) and the stingarees (Urolophidae; 3 species). Chondrichthyan bycatch was highly variable between fishery sectors; catch rates were low in the tiger/Endeavour prawn sector (north Queensland; 0.02–0.12 individuals ha-1 trawled) and in the eastern king prawn (deepwater) sector (southern Queensland; 0.08 individuals ha-1 trawled), intermediate in Hervey Bay (southern Queensland; 0.25 individuals ha-1 trawled) and in the scallop sector (central Queensland coast; 0.31 individuals ha-1 trawled) and highest in the eastern king prawn (shallow water) sector (southern Queensland; 0.96 individuals ha-1 trawled). Chondrichthyan bycatch in the eastern king prawn (shallow water) sector was dominated by the three batoids Aptychotrema rostrata, Trygonoptera testacea and Urolophus kapalensis (~92% of the chondrichthyan bycatch by number), in the eastern king prawn (deepwater) sector by the skate Dipturus polyommata and the two catsharks Asymbolus rubiginosus and Figaro boardmani (~83% of the chondrichthyan bycatch by number), in the scallop sector by the three batoids A. rostrata, Neotrygon kuhlii and Neotrygon picta (~91% of the chondrichthyan bycatch by number), and in the tiger/Endeavour prawn sector by the two batoids Himantura astra and Gymnura australis and the two sharks Chiloscyllium punctatum and Hemigaleus australiensis (~67% of the chondrichthyan bycatch by number). The testing of TEDs and BRDs, which are mandatory throughout the fishery, demonstrated only a limited ability to reduce chondrichthyan bycatch in the ECTF, which is comprised mainly of relatively small species. The shorter trawl durations of the surveys compared with normal commercial activities may have under-represented larger species. No significant reductions in chondrichthyan bycatch were found using a TED and a radial escape section BRD in the eastern king prawn (shallow water) sector, using a TED and a square-mesh codend BRD in the eastern king prawn (deepwater) sector, or using a TED and a fisheye BRD in Hervey Bay. There was however, a significant difference in the probability of capturing the group ‘sharks and guitarfishes’ (comprised largely of A. rostrata) between codend types in the scallop sector, with the lowest probability of capture in nets fitted with both a TED and a square-mesh codend BRD (the difference was largely attributed to the effects of the TED). In the tiger/Endeavour prawn sector, in which three different BRDs were trialed (fisheye, square-mesh codend, square-mesh panel), the probability of capturing chondrichthyans was significantly lower in nets fitted with a fisheye BRD than in the standard (control) net, and the probability of capturing batoids was significantly lower in nets fitted with a fisheye BRD or with a square-mesh codend BRD than in the standard (control) net. The small sample size of chondrichthyan catches in some sectors may have reduced to power to detect bycatch reduction. The biology of several bycatch species from the families Rajidae, Rhinobatidae, Urolophidae and Scyliorhinidae was examined. For D. polyommata, size at birth was estimated at ~100–110 mm total length (LT), size at first feeding at ~105–110mm LT, size at 50% maturity (LT50 and 95% CI) at 321 (305–332) mm LT for females and 300 (285–306) mm LT for males. Diet (described by the index of relative importance as a percentage) was predominantly crustacean based, with carid shrimps (53.6%) and penaeoid prawns (23.3%) being the most significant prey groups. For A. rostrata, size at birth was estimated at <170 mm LT, size at 50% maturity (LT50 and 95% CI) at 640 (618–663) mm LT for females and 597 (551–649) mm LT for males, and litter size was 9–20 (n = 9; mean ± S.E. = 15.1 ± 1.2). For T. testacea, size at birth was estimated at 77–100 mm disc width (WD), size at 50% maturity (WD50 and 95% CI) at 163 (156–169) mm WD for females and 146 (140–150) mm WD for males, and litter size was always one (n = 6). For U. kapalensis, size at birth was estimated at 75–100 mm WD, size at 50% maturity (WD50 and 95% CI) at 154 (145–160) mm WD for females and 155 (149–159) mm WD for males, and litter size was always one (n = 16). The catsharks A. analis, A. rubiginosus and F. boardmani were all confirmed as single oviparous species (carrying only one egg case in each uterus at one time). Ovarian fecundity (the number of vitellogenic follicles) averaged 13.6 (range 13–20) in A. analis, 13.5 (range 5–23) in A. rubiginosus and 10.4 (range 9–13) in F. boardmani. While only limited data were available from southern Queensland, several indicators suggest that Asymbolus catsharks are reproductively active year-round. A general lack of small-sized or immature catsharks captured during the study made assessments of size at maturity difficult for these species. The conservation status of ECTF bycatch species was examined through the application of the IUCN Red List of Threatened SpeciesTM Categories and Criteria, which considers extinction risk at the global level. Of the 24 ECTF chondrichthyan bycatch species evaluated against the IUCN Red List Categories and Criteria, four have been assessed globally as Vulnerable (a threatened category indicating that a species is ‘facing a high risk of extinction in the wild’), seven as Near Threatened, 11 as Least Concern and two as Data Deficient. While the four globally threatened species (A. nichofii, Heteroscyllium colcloughi, Rhynchobatus australiae and Urolophus sufflavus) were only minor components of the ECTF bycatch, their global conservation status warrants that fisheries management and industry should act to ensure minimal impacts on these species. An ecological risk assessment method (Susceptibility-Recovery Analysis) was used to assess the relative sustainability or risk of individual species to the fishing activities of the ECTF. Two separate approaches were taken to the technique, which considers sustainability to be dependent on the susceptibility of a species to the fishery and the recovery potential of a species after depletion by fishing activities. The first approach applied the precautionary principal when data were lacking for the calculation of recovery attributes, while the second used biological data from similar species when species-specific data were lacking. The precautionary approach tended to overestimate risk to poorly known oviparous species. The biological approach suggested that A. nichofii, F. boardmani, Rhizoprionodon acutus, Rhizoprionodon taylori and Rhynchobatus palpebratus face the least risk (i.e. were the most sustainable) while several medium-large batoids and the sharks Loxodon macrorhinus and Heteroscyllium colcloughi were the species most at risk (i.e. least sustainable). Demonstrating ecological sustainability of the ECTF will need to be a continued management objective into the future. To further improve the ecological sustainability of the fishery in relation to sharks, batoids and holocephalans, a number of management recommendations are proposed: (1) give warranted conservation consideration to listed threatened species as well as species identified as being at risk; (2) expand required logbook information on chondrichthyan species to include recording of catches of these species; (3) encourage safe release practices for all chondrichthyans to maximise survivorship of discards; (4) initiate research into the survivorship of discards; (5) ensure long-term observer coverage on commercial vessels to monitor bycatch levels; and, (6) test and quantify reduced TED bar spacings (presently 120 mm) in fishery sectors which show the highest chondrichthyan bycatch levels, that is, the eastern king prawn (shallow water) and scallop sectors.

Some of the key elements to assess the status of any wildlife population in a given geographical area are the levels of recruitment, survival and mortality. Whilst most of the information on marine turtles has been obtained from nesting sites, turtles spend most of their lives at sea. The conservation status of marine turtles in the southeast Pacific is poorly documented. This is particularly true for countries like Peru, where nesting events are very rare, although five species of turtles from populations from all over the Pacific basin, use these waters as foraging grounds. Little information exists on the threats to turtle populations in foraging areas or the magnitude of these impacts. Small-scale fisheries are a globally important economic activity serving as a source of food and employment for ca. 1 billion people; however we show that they also have serious impacts on marine turtle populations from all over the Pacific basin in the form of incidentally captured marine turtles. The five chapters that constitute this thesis are intended to increase our understanding of small-scale fisheries impacts on this taxon during their aquatic life stages. This work focuses on describing these fisheries, their impacts on marine turtles and proposes methodologies to monitor and assess the level of bycatch from small-scale fisheries. We also discuss alternative ways to prevent fisheries interactions and promote the involvement of artisanal fishermen in the southeast Pacific in implementing conservation solutions.