Carcharias taurus is listed as Critically Endangered along the east coast of Australia and there is concern about their status globally. The use of traditional tag–recapture methods to monitor the east coast C. taurus population have been discontinued due to tag–biofouling and injuries that relate to tag attachment. In the current study, captive and wild C. taurus were used to assess whether spots present on their flanks were suitable natural tags for individual shark recognition. Photographic images of seven captive sharks taken at monthly intervals for 13 months and at three years after the start of the study indicated that their spot number, position and relative size did not change over this period. Similarly, eighty–nine wild sharks photographically re–identified at least 23 months after their initial identification (and in one case after 14 years) confirmed long–term spot–pattern retention. Photographic recaptures of individual C. taurus provided information about their temporal and spatial distribution and movement patterns along the Australian east coast in relation to maturity, sex and reproductive condition. A total of 930 sharks were photo–identified between 2004 and 2008 at 23 aggregation sites between Wolf Rock and Montague Island. Of these, 479 were females (271 mature, 208 immature) and 452 were males (288 mature, 60 sub–adults, 104 juveniles). The distribution of pregnant C. taurus was seasonally and temporally distinct from all other sharks. Visibly pregnant C. taurus were recorded at Wolf Rock (the most northern site) from February until October, although many sharks left during July. Pregnant C. taurus were also observed at North Moreton Island, Flat Rock and Fish Rock between June and November. Resting (mature, non–gravid) females and mature males were mostly observed at mid–southern sites from December to June, with northern counts increasing from June to November. The majority of immature sharks were recorded at mid–southern sites. Of 930 sharks identified between 2004 and 2008, 149 were identified at more than one site. On average, mature females moved 338 km (SD ± 465), mature males 340 km (SD ± 299), immature females 147 km (SD ± 98), sub–adult males 185 km (SD ± 216), and juvenile males 271 km (SD ± 237). The maximum rate of movement per day was 18.5 km for a mature female shark, 20.7 km for a mature male, 4.3 km for an immature female, 86 km for a sub–adult male and 4 km for a juvenile male. Mature males and mature non–pregnant females tended to move north from mid–winter and mate in late spring/early summer in warmer waters. From about mid–winter, pregnant females began to move from the warmer waters of their gestation areas to cooler southern waters to pup (probably from late spring to mid–summer). The movement patterns of immature sharks varied temporally, and were more limited spatially. Underwater censuses, photo–identification and acoustic tracking of individual C. taurus were used to investigate their reproductive periodicity, localised movements and behavioural segregation at Wolf Rock – the most northerly aggregation site on the east Australian seaboard. A biennial reproductive cycle was indicated for 18 of 28 females for which re–identifications spanned at least two mating and/or pregnancy events. Nine of the 28 sharks appeared to exhibit a triennial reproductive cycle. Male C. taurus were observed between July and January, but were absent between February and April. Scuba divers reported seeing some mating scars on individuals from mid–October, however fresh mating scars were predominately observed on photographs of individual C. taurus taken in November and December. Four acoustically–tagged mature female sharks remained within 500 m of the Wolf Rock aggregation site within a marine sanctuary zone for 78 – 90 % of the 11–15 day study period. A minimum population estimate of 930 individuals is provided from all sharks identified between 2004 and 2008. In addition, a Jolly–Seber (open model design) mark–recapture analysis on data obtained during four scheduled photo–identification surveys (conducted between July 2006 and February 2008 at 25 aggregation sites along the east coast of Australia) was used to estimate the size of this population. A maximum of 272 sharks (143 females and 129 males) were identified during any scheduled survey period. Model averaging across the highest rated JS models (Popan data formulation) resulted in an estimate of 756 males (95% CI = 590 – 922) and 1185 females (95% CI = 901 – 1469). The mark–recapture abundance estimate is considered preliminary and requires further model development to incorporate the heterogeneity in distribution and migration patterns within the C. taurus population. The occurrence of retained fishing gear and gear–related jaw injuries were quantified from the four scheduled photo–identification surveys along the east coast of Australia. A total of 673 sharks were identified with 119 occurrences of retained fishing gear or jaw injury recorded from 113 individual sharks. For sharks that were known by spot–patterns on both flanks, 29 % of females and 52 % of males were seen with retained fishing gear or a gear–related jaw injury. The largest numbers of identified sharks (222) during the surveys were seen at Fish Rock (off the New South Wales coast): 48 % of all sharks identified with retained fishing gear were first identified at this site. Fish Rock is a designated critical habitat for C. taurus, but most forms of line fishing, except fishing while anchored or moored with bait and/or wire trace line are permitted. Results from the surveys clearly demonstrated that C. taurus is susceptible to a large variety of fishing gear and fishing methods. Current protection measures for C. taurus appear insufficient at this site, particularly as large aggregations that include immature and mature sharks occur consistently throughout the year.

A characterization reproductive of fish study may help in determination of recurring patterns of behavior and to facilitate response predictions to demographic disturbance in the spatial and temporal scales in determined zoogeographical area. Therefore, the objective was to identify the reproductive aspects of bycatch exploited by driftnet fishing community of Jaraguá, Maceió / Alagoas. To that end, samples were collected in two boats per month from December 2009 to November 2010. 2149 fish, 51 species and 25 families were collected, being the most abundant family Haemulidae. The high selectivity of gill nets resulted in a low range of total length (150-601 mm). Among the most abundant species (n &#8805; 30) the number of females was significantly higher (p <0.05), except B. marinus. We suggest the occurrence of split spawning for A. vulpes, B. marinus, C. chrysurus, C. nobilis, E. alletteratus, H. parrai, H. plumieri, O. oglinum, O. ruber and P. corvinaeformis. Recorded little fluctuation of the values of Gonadosomatic Index, Condition Factor and Repletion index, per season, which agrees with the expected for tropical regions. A portion of young individuals of E. alletteratus, A. vulpes and C. crysos indicates that driftnet fishing in the area does not meet any standard of maturity in relation to the capture of species. Identified were three groups of species, according to results of PCA, explained mainly by the size at first maturity, and comprimeto total gonad weight, contained in factor 1 explains 50.74% variance. The variance index of reproductive activity values suggest that P.maculatus, C. crysos and O. ruber species are most vulnerable to the impact of fishing on reproductive activity. Thus, these fisheries are at risk of impact on the reproductive process of harvested species, highlighting the need to implement regulatory measures for fisheries with gillnets in Alagoas. / Fundação de Amparo a Pesquisa do Estado de Alagoas / A caracterização reprodutiva dos peixes pode ajudar na determinação de padrões recorrentes e facilitar previsões sobre respostas a perturbações demográficas nas escalas espaciais e temporais em determinada dada área zoogeográfica. Diante disso, o objetivo do trabalho foi identificar aspectos reprodutivos da ictiofauna acompanhante explotada pela pesca de emalhe da frota artesanal de Jaraguá, Maceió/Alagoas. Para tanto, coletas mensais do desembarque foram realizadas entre dezembro de 2009 e novembro de 2010. Foram coletados 2149 peixes, de 51 espécies e 24 famílias, sendo Haemulidae a família mais abundante. A alta seletividade da rede de emalhe resultou em uma amplitude estreita de comprimento total (150 - 601 mm). Dentre as espécies mais abundantes (n&#8805;30) o número de fêmeas foi significativamente maior (p<0,05), com exceção de B. marinus. Sugere-se a ocorrência de desova parcelada para A. vulpes, B. marinus, C. chrysurus, C. nobilis, E. alletteratus, H. parrai, H. plumieri, O. oglinum, O. ruber e P. corvinaeformis. Registrou-se pouca flutuação sazonal dos valores do Índice Gonadossomático, Fator de Condição e Índice de Repleção Estomacal, fato característico das regiões tropicais. Uma parcela de indivíduos jovens de E. alletteratus, A. vulpes e C. crysos indica que as capturas da pesca de emalhe na área não atende a nenhum padrão relacionado à maturidade das espécies. Identificaram-se três grupos de espécies, conforme os resultados da PCA, explicados principalmente pelo tamanho de primeira maturação, comprimento total e peso das gônadas, contidos no fator 1que explica 50,74% da variância. As variações do índice de atividade reprodutiva sugerem que O. ruber, C. crysos e P. maculatus são as espécies mais vulneráveis ao impacto da pesca. Sendo assim, estas pescarias apresentam risco de impacto sobre o processo reprodutivo das espécies capturadas, destacando a necessidade da implantação de medidas reguladoras das pescarias com rede de emalhe em Alagoas.

The bycatch of cetaceans in fishing gear is considered to be one of the biggest conservation threats to these species. Gear modifications have the potential to reduce these bycatches in global fisheries but there is little available information on how such modifications may change the fishing performance of gear, or indeed the behavior of cetaceans interacting with fishing gear. Generalized linear models (GLMs) were used to identify factors related to cetacean bycatches in UK bottom set gillnets. Rigged net height had a significant positive relationship with harbour porpoise (Phocoena phocoena) bycatch in ICES Area VII suggesting that lowering the profile of gillnets may have the potential to reduce bycatch rates. Modifications to gillnets, such as changing the amount of floatation or increasing the density of the meshes, were found to have significant effects on the active fishing heights of these nets. However, results from a bycatch mitigation trial in Argentina showed that the reduced fishing profile of one experimental net did not result in a concurrent reduction in the bycatch rate of Franciscana dolphins (Pontoporia blainvillei). While there was no significant difference in the rate, length or intensity of harbour porpoise encounters in the presence or absence of gillnets, the proportion of fast echolocation click trains were significantly higher when a net was present, indicating that porpoises either increased acoustic inspection of the net or foraging in the vicinity of the net. An analysis of underwater video footage collected inside trawl nets in an Australia fishery showed that bottlenose dolphins (Tursiops sp.) were present inside nets more frequently than they were caught and were actively foraging inside these nets. The orientation of dolphins inside these nets indicates that the current design of excluder devices used in this fishery could be improved to further reduce bycatch rates.

Made available in DSpace on 2014-12-17T14:02:03Z (GMT). No. of bitstreams: 1 RodrigoC.pdf: 1253605 bytes, checksum: 901bba0a33ba9a917533656bc7e7c6b0 (MD5) Previous issue date: 2006-12-08 / The marine turtles biological characteristics and the impact they have been suffering in consequence of human activities have caused in the last decades the decrease of populations to unsustainable levels. All four of the species described in this paper are registered as endangered in a list by IUCN: Caretta caretta, Lepidochelys olivacea, Chelonia mydas, Dermochelys coriacea. The main causes of such impact include several fishing activities, mostly the surface longline. This paper discusses the monitoring of two foreigner longline fleet along the North East Brazilian coast between October of 2004 and September of 2005. Both operated in the West South Atlantic, one using the Chinese technique and the other the American. The American method s target species is the swordfish (Xiphias gladius), and it is characterized by using squid as bait, J 9/0 offset 5? hook, light sticks and night soaking. It also operates in shallower waters than the Chinese method. The source of information about the efforts and the catches came from onboard observers and were used to calculate the catching rate of turtles over 1000 hooks (CPUE). The American equipment caught more turtles (CPUE = 0,059; N= 103), mainly D. coriacea, while the Chinese longline caught mainly the L. olivacea and presented a CPUE= 0,018 (N= 89). The hooks were most frequently found attached to the mouth of C. caretta, C. mydas, and L. olivacea. The D. coriacea were most frequently caught by hooks externally attached to different parts of their body. There was no significant difference between the hook type catching and most turtles were still alive when released. The results suggest a greater potential of turtle catching by the American method. Besides the statistic tests have showed less interaction between the Chinese equipment and marine turtles, the catches of this fishing technique could have been underestimated due to miscommunication between the onboard observer and the vessel s crew plus the retrieve of the longline during night time / As caracter?sticas biol?gicas das tartarugas marinhas em conjunto com as diversas perturba??es antr?pica sofridas ao longo do tempo t?m reduzido v?rias popula??es para n?veis quase invi?veis de se manterem, atualmente, as quatro esp?cies registradas nesse trabalho s?o citadas na lista de fauna amea?ada da Uni?o Internacional para Conserva??o da Natureza - IUCN (Caretta caretta, Chelonia mydas, Dermochelys coriacea e Lepidochelys olivacea). Entre os principais riscos que est?o sujeitas as tartarugas marinhas podemos citar as atividades pesqueiras de maneira geral e em especial o espinhel pel?gico de superf?cie. O presente estudo apresenta o monitoramento realizado junto a duas frotas estrangeiras de espinhel de superf?cie sediadas no nordeste do Brasil, ente outubro de 2004 e setembro de 2005. Ambas atuaram no Atl?ntico Sul Ocidental, sendo que o espinhel chin?s teve como objetivo a captura de atuns (Thunnus spp), utilizando peixe como isca, anzol tipo tunna hook e imers?o do petrecho de pesca durante o dia. A esp?cie alvo do petrecho chamado de americano foi o espadarte (Xiphias gladius), que se caracterizou por utilizar lula como isca, anzol tipo J 9/0 offset 5?, atrator luminoso, imers?o noturna e mais rasa do que o chin?s. As informa??es a respeito do esfor?o e das capturas foram provenientes de observadores de bordo e utilizadas para calcular os ?ndices de capturas de tartarugas por 1000 anz?is (CPUE). O petrecho americano capturou mais tartarugas (CPUE= 0,059, N= 113) e foi mais representado por D. coriacea, enquanto o espinhel chin?s apresentou CPUE = 0,018 (N= 89) e L. olivacea como a esp?cie mais numerosa. O local mais comum de insers?o do anzol em C. caretta, C. mydas e L. olivacea foi a boca. As D.coriacea foram mais capturadas quando o anzol se prendeu externamente. N?o houve diferen?a significativa das capturas conforme o tipo de anzol, e os indiv?duos liberados vivos predominaram. Os resultados encontrados corroboram com o maior potencial de capturas de tartarugas atribu?do ?s caracter?sticas do petrecho que tem como alvo os espadartes. No entanto, testes estat?sticos demonstraram que, apesar do petrecho voltado ? captura de atuns interagir menos com tartarugas marinhas, as capturas na pescaria chinesa foram subestimadas devido ? dificuldade de comunica??o do observador com a tripula??o e recolhimento do espinhel durante a noite