Abstract Studies relating the populational structure of target species to operational and environmental variables contribute directly to the management of the fisheries in these resources. Therefore, this study aimed to provide data on fishing and ecology of the swordfish ( Xiphias gladius) caught by the Brazilian longline fleet operating in the western Atlantic between 2010 and 2016. Generalized additive mixed models were used to evaluate the relationship between explanatory variables and responses based on Catch Per Unit of Effort (CPUE) data. Results show that the Brazilian longline fleet catches the swordfish mostly between latitudes of 5°N to 30°S and longitudes of 20° to 50°W and that the swordfish prefers temperatures under 25°C at depths below 60 meters. The species showed a tendency toward intermediate light intensity, predominating in the crescent moon phase, and a preference for areas with low chlorophyll concentrations. Our findings on operational and environmental interactions with swordfish CPUE suggest areas and times that can be used by fishing fleets and government institutions as a starting point for swordfish management strategies.

ABSTRACT Longlines bearing “hook timers” (HTs) and alternating circle (15/0 and 17/0) and “J” (10/0) hooks were employed off the coast of Brazil to measure differences in fishing mortality associated with hook type and on-hook time between capture and boarding. A total of 431 HTs were activated, revealing a clear pattern of the increased mortality rate of fishes associated with increased on-hook time. Swordfish had high mortality rates, unlike blue sharks, which had low mortality rates regardless of hook type and the location in which the hook was transfixed. The six species of tunas and billfishes examined in this study showed a strong association between hooking location and the animal's release condition, with reduced mortality associated with individuals hooked externally. Results suggest that knowledge of factors affecting the survival of pelagic fishes caught in longline fisheries may enable the development and adoption of fishing methods to reduce mortality of longline bycatch.

Quatro exemplares de agulhão-vela foram marcados com marcas eletrônicas monitoradas por satélite ('Pop-up satellite archival tags - PSATs') nas águas costeiras do Rio de Janeiro, sudeste do Brasil, durante janeiro e fevereiro de 2009 (agulhão-vela I e II) e entre novembro de 2010 e janeiro de 2011 (agulhão-vela III e IV). O número total de dias monitorados (ou seja, o tempo que as marcas permaneceram implantadas nos peixes) foram 12 (agulhão-vela I), 51 (agulhão-vela II), 16 (agulhão-vela III) e 43 dias (agulhão-vela IV). Os resultados demonstram um padrão claro de utilização do hábitat com a maior parte do tempo despendido predominantemente próximo à superfície do mar ocupando águas com uma faixa de temperatura restrita. Apesar da preferência por águas superficiais, os agulhões frequentemente realizaram mergulhos para águas mais profundas (ca. > 50 m) em intervalos de três a seis horas. A "rota mais provável" estimada a partir dos dados brutos de geolocalização e o modelo 'State-Space Kalman Filter' sugerem que os agulhões marcados não realizaram migrações significativas a partir do local de marcação. Em resumo, nossos resultados apresentam informações sobre a biologia da espécie no Atlântico Sudoeste e como as migrações verticais durante o dia e a noite são influenciadas pela temperatura da água e como essa informação pode auxiliar as avaliações de estoques de agulhão-vela no sudoeste do Atlântico.

Pop-up satellite archival tags (PSATs) were deployed on four sailfish, Istiophorus platypterus, in the coastal waters of Rio de Janeiro State in southeast Brazil during January and February of 2009 (sailfish I and II) and between November 2010 and January 2011 (sailfish III and IV). The total number of days monitored (i.e., time that the tags remained attached) were 12 (sailfish I), 51 (sailfish II), 16 (sailfish III) and 43 days (sailfish IV). The results indicate a clear pattern of vertical habitat utilization with the majority of the time spent concentrated near the uniform sea surface layer occupying a relatively narrow temperature range. Despite the clear preference for epipelagic surface waters, sailfish regularly undertook vertical excursions into deeper waters (>50 m) within three to six hour intervals. "Most Probable Tracks" (estimated from raw geolocations using the state-space Kalman filter model) and linear displacements suggested that tagged sailfish did not move significant distances from the tagging site. In brief, our report provides information regarding the biology of sailfish in the southwestern Atlantic and how vertical distributions during the day and night are influenced by water temperature and how this information can improve sailfish stock assessments in southwestern Atlantic Ocean.

No presente estudo, uma análise de agrupamento foi utilizada para classificar 6.486 lances feitos pela frota espinheleira sediada no Estado de São Paulo, Brasil, de 1998 até 2006, em relação à composição das espécies presentes nas capturas. Baseado nas proporções de doze espécies e três grupos de espécies, três agrupamentos foram identificados: C1: outros peixes; C2: tubarão-azul; C3: espadarte. Os resultados indicaram que ao longo do período estudado, a frota direcionou suas capturas principalmente para o tubarão-azul e para o espadarte, além de terem evidenciado que a importância do tubarão-azul nessa pescaria tem crescido progressivamente ao longo dos anos. Áreas mais afastadas da costa foram exploradas principalmente no primeiro e quarto trimestres (em especial a partir de 2001), enquanto que um esforço de pesca mais concentrado perto da quebra da plataforma continental foi observado durante o segundo e terceiro trimestres (para todo o período estudado). A frota espinheleira sediada em São Paulo mudou a estratégia de pesca para diferentes espécies-alvo, o que produziu importantes mudanças nas principais espécies capturadas por esforço de pesca (CPUE). A análise de agrupamento parece ter identificado apropriadamente essas alterações ao longo do tempo, em relação às quais não há, em geral, qualquer informação nos mapas de bordo.

In the present study, a cluster analysis, in relation to the species composition of the catches, was used to classify 6,486 fishing sets by a longline fleet based in São Paulo State, Brazil, from 1998 to 2006. Based on the proportions of 12 species and three broader species groups, three clusters were identified: C1: other fishes; C2: blue shark; C3: swordfish. Results indicated that the fleet targeted mainly blue shark and swordfish and also showed that the blue shark importance in this fishery has been growing progressively trough the years. Offshore areas were exploited mainly in the first and fourth quarters (from 2001 mainly), while the fishing effort was more concentrated near the continental shelf break, during the second and third quarters (for the whole period). The longline fishery based in Sao Paulo State changed fishing strategy to target different species which produced important changes in catch-per-unit-effort (CPUE) of the main species caught. Cluster analysis seems to have appropriately identified these changes over time, which is an important information, often missing in logbooks.