Fishing methods to reduce sea turtle mortality associated with pelagic longlines

Watson, John W.; Epperly, Sheryan P.; Shah, Arvind; Foster, Daniel G.

doi:10.1139/f05-004

Cited by 249 publications

(421 citation statements)

References 5 publications

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“…During this time, U.S. government-sponsored research was conducted in the NED that provided evidence that the use of a relatively large (18/0) circle hook in combination with ∼200-500 g Atlantic mackerel (Scomber scombrus) bait could significantly reduce bycatch rates of both loggerhead and leatherback sea turtles (Watson et al, 2005). Additionally, hook-and-bait combinations were also found to decrease the proportion of deeply ingested hooks in loggerhead turtles (Watson et al, 2005), thereby presumably increasing the rates of post-interaction survival. Based on these findings, both previously closed areas in the North Pacific and NED area of the Atlantic were re-opened with required use of circle hooks with minimum width dimensions equivalent to an 18/0 size hook (∼4.9 cm).…”

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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Section: Introductionmentioning

confidence: 99%

Sea Turtle Bycatch Mitigation in U.S. Longline Fisheries

et al. 2017

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“…The SST, in turn, has been shown to affect local loggerhead abundance patterns (e.g. Watson et al, 2005;Hawkes et al, 2007a).…”

Section: Introductionmentioning

confidence: 99%

The North Atlantic Oscillation and sea surface temperature affect loggerhead abundance around the Strait of Gibraltar

Báez¹,

Bellido²,

Ferri‐Yáñez³

et al. 2011

Sci. Mar.

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“…Therefore, many nesting beaches are particularly susceptible to coastal hazards such as storm surges and coastal erosion. However, although much effort has been expended over the last two decades to understand and mitigate the threats to marine turtles (Watson et al, 2005), the threat of climate change on this taxon has, until recently, been given little attention (for more information, see Hawkes et al, 2009). Studies of the effects of global warming on sea turtle populations have focused essentially on the loss of nesting beach habitat as a result of an increase in sea level and on the changes in sex ratio (Daniels et al, 1993;Davenport, 1997;Nicholls, 1998;Nicholls et al, 1999;Fish et al, 2005Fish et al, , 2008Baker et al, 2006;Jones et al, 2007;Mazaris et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Effect of tidal overwash on the embryonic development of leatherback turtles in French Guiana

Caut

Guirlet

Girondot

2010

Marine Environmental Research

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a b s t r a c tIn marine turtles, the physical conditions experienced by eggs during incubation affect embryonic development. In the leatherback, hatching success is known to be low in relation to other marine turtles as a result of high embryonic mortality. Moreover, the hatching success on Yalimapo in French Guiana, one major nesting beach for this species, is lower compared to other nesting sites. We assessed the rate of leatherback turtle embryonic mortality in order to investigate the tolerance of leatherback turtle clutches laid on Yalimapo beach to tidal overwash, and we highlight causes of poor hatching success. Of the 89 nests studied, 27 were overlapped by tide at least once during the incubation period (of which five nests were lost by erosion). The hatching success was on average significantly lower in overwashed nests than in non-overwashed, highlighting the existence of embryonic developmental arrest linked to tidal inundation. The stages of developmental arrest and their proportion are linked with time, frequency and level of overwash events. In the context of global warming and associated sea-level rise, understanding the detrimental effect of tidal inundation on the development of marine turtle nests is of interest in nesting sites where turtles are likely to be forced to nest closer to the tide line, thus exposing their nests to greater risk of nest overlap with sea and tidal inundation.

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Fishing methods to reduce sea turtle mortality associated with pelagic longlines

Cited by 249 publications

References 5 publications

Sea Turtle Bycatch Mitigation in U.S. Longline Fisheries

Sea Turtle Bycatch Mitigation in U.S. Longline Fisheries

The North Atlantic Oscillation and sea surface temperature affect loggerhead abundance around the Strait of Gibraltar

Effect of tidal overwash on the embryonic development of leatherback turtles in French Guiana

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