Differential loggerhead by-catch and direct mortality due to surface longlines according to boat strata and gear type

Camiñas, Juan Antonio; Báez, José C.; Valeiras, X.; Real, Raimundo

doi:10.3989/scimar.2006.70n4661

Cited by 53 publications

(55 citation statements)

References 6 publications

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“…incidental catches/no. fishing operations; Camiñas et al 2006). In index F, a fishing operation refers to all procedures performed between deploying a longline set and retrieving all of the gear, which is usually carried out in < 20 h on average.…”

Section: Methodsmentioning

confidence: 99%

Loggerhead turtle by-catch depends on distance to the coast, independent of fishing effort: implications for conservation and fisheries management

Báez¹,

Real²,

García-Soto³

et al. 2007

Mar. Ecol. Prog. Ser.

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Drifting longline is considered one of the most dangerous fishing gears for marine turtles and is their principal threat in the western Mediterranean Sea. During the summers of 2000 to 2003, 179 fishing operations were observed onboard a traditional Spanish drifting longline boat in the Balearic Sea (western Mediterranean) to analyse the effects of fishing effort and ecogeographical factors on the by-catch of loggerhead turtles Caretta caretta. We observed 4074 swordfish captured and 675 loggerhead turtles by-caught. The probability of catching at least 1 loggerhead was related to the distance of the fishing-ground to the coast and, to a lesser extent, depth, both independent of fishing effort. The average number of loggerheads captured was spatially structured only according to mean distance to the coast. However, the number of swordfish captured was correlated with fishing effort but was not correlated with distance to the coast or depth. Distance to the coast was correlated with gear retrieval time, sea surface temperature and velocity, and phytoplankton concentration. As the number of loggerheads captured was independent of the number of hooks, the number of fishing operations was a better unit than the number of hooks to assess loggerhead by-catch. Limiting drifting longline fishing activity to within 35 international nautical miles from the coast could reduce loggerhead by-catch substantially without affecting swordfish captures and with little resistance from fishermen.KEY WORDS: By-catch · Drifting longline · Sea turtle · Loggerhead · Caretta caretta · South-western Mediterranean · Swordfish fishery Resale or republication not permitted without written consent of the publisher

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Section: Methodsmentioning

confidence: 99%

Loggerhead turtle by-catch depends on distance to the coast, independent of fishing effort: implications for conservation and fisheries management

Báez¹,

Real²,

García-Soto³

et al. 2007

Mar. Ecol. Prog. Ser.

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“…Pelagic longline fishing, a gear type present in all the world's oceans, is directly associated with high rates of bycatch and variable rates of mortality of sea turtles (Camiñas et al, 2006;Swimmer and Gilman, 2012). Sea turtle vulnerabilities to longline fishing gear are dependent on gear configuration as well as the species' geospatial, temporal, and vertical depth distributions (Wallace et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Sea Turtle Bycatch Mitigation in U.S. Longline Fisheries

et al. 2017

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Capture of sea turtles in longline fisheries has been implicated in population declines of loggerhead (Caretta caretta) and leatherback (Dermochelys coriacea) turtles. Since 2004, United States (U.S.) longline vessels targeting swordfish and tunas in the Pacific and regions in the Atlantic Ocean have operated under extensive fisheries regulations to reduce the capture and mortality of endangered and threatened sea turtles. We analyzed 20 + years of longline observer data from both ocean basins during periods before and after the regulations to assess the effectiveness of the regulations. Using generalized additive mixed models (GAMMs), we investigated relationships between the probability of expected turtle interactions and operational components such as fishing location, hook type, bait type, sea surface temperature, and use of light sticks. GAMMs identified a two to three-fold lower probability of expected capture of loggerhead and leatherback turtle bycatch in the Atlantic and Pacific when circle hooks are used (vs. J hook). Use of fish bait (vs. squid) was also found to significantly reduce the capture probability of loggerheads in both ocean basins, and for leatherbacks in the Atlantic only. Capture probabilities are lowest when using a combination of circle hook and fish bait. Influences of light sticks, hook depth, geographic location, and sea surface temperature are discussed specific to species and regions. Results confirmed that in two U.S.-managed longline fisheries, rates of sea turtle bycatch significantly declined after the regulations. In the Atlantic (all regions), rates declined by 40 and 61% for leatherback and loggerhead turtles, respectively, after the regulations. Within the NED area alone, where additional restrictions include a large circle hook (18/0) and limited use of squid bait, rates declined by 64 and 55% for leatherback and loggerhead turtles, respectively. Gains were even more pronounced for the Pacific shallow set fishery, where mean bycatch rates declined by 84 and 95%, for leatherback and loggerhead turtles, respectively, for the post-regulation period. Similar management approaches could be used within regional fisheries management organizations to reduce capture of sea turtles and to promote sustainable fisheries on a global scale.

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“…Many studies indicate that the Spanish longline fleet is concentrated mainly around the Balearic Islands (Camiñas et al 2006, Báez et al 2007a, 2007b, García-Barcelona et al 2010, Báez et al 2013b. Thus, Alboran Sea was used by approximately 5% of the operative fleet; while Balearic Sea was used by approximately 80% of the operative fleet.…”

Section: Discussionmentioning

confidence: 99%

“…Vessel length range from 12 to 27 m and fishing trips are often of short duration (one day to six days). A major description of these gears and fisheries are available in Camiñas et al (2006), Báez et al (2007a, b), García-Barcelona et al (2010), and Báez et al (2013b).…”

Section: Methodsmentioning

confidence: 99%

Assessing the influence of the atmospheric oscillations on pelagic and highly migratory sharks bycatches from Spanish Mediterranean Sea, a meta-analytic approach

Báez¹

2015

analesbio

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Evaluación de la influencia de las oscilaciones atmosféricas sobre las capturas accesorias de tiburones pelágicos y altamente migratorios desde el Mediterráneo español, un enfoque metaanalíticoEl objetivo principal del presente estudio fue analizar el efecto de las oscilaciones atmosféricas sobre los patrones de descarga de los tiburones pelágicos capturados de forma accesoria en palangre de superficie (fundamentalmente tintoreras, marrajos, y tiburones zorros) desde el Mediterráneo español, utilizando un enfoque meta-analítico. El objetivo final es conocer la respuesta de los tiburones altamente migratorios a los fenómenos climáticos de gran escala, y su posible relación con el efecto del calentamiento global. Se utilizaron dos fuentes de datos diferentes, ambas de áreas geográficas diferentes: mar de Alborán y mar Balear. Los resultados indican que la abundancia local de tiburones pelágicos podría estar mediada por la oscilación ártica.Palabras clave: Oscilación ártica, Calentamiento Global, Oscilación del Atlántico Norte, tiburones. AbstractBlue shark, shortfin mako shark and the thresher sharks are the three taxa of pelagic sharks most caught as bycatch in the Spanish pelagic longline fishery from Mediterranean Sea. The main aim of the present study was to analyse the effect of atmospheric oscillations about landing patterns of blue shark, shortfin mako shark, and thresher sharks from Spanish Mediterranean Sea, using a metaanalytical approach. The ultimate goal was to understand the response of highly migratory sharks to large-scale climate phenomena, and its possible link with the effect of global warming. Two different data sources were used from different geographical areas: Alboran Sea and Balearic Sea. The results indicate that the local abundance of pelagic sharks could be mediated by the Arctic Oscillation.

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Differential loggerhead by-catch and direct mortality due to surface longlines according to boat strata and gear type

Cited by 53 publications

References 6 publications

Loggerhead turtle by-catch depends on distance to the coast, independent of fishing effort: implications for conservation and fisheries management

Loggerhead turtle by-catch depends on distance to the coast, independent of fishing effort: implications for conservation and fisheries management

Sea Turtle Bycatch Mitigation in U.S. Longline Fisheries

Assessing the influence of the atmospheric oscillations on pelagic and highly migratory sharks bycatches from Spanish Mediterranean Sea, a meta-analytic approach

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