Effects of chemicals from longline baits on the biting behaviour of loggerhead sea turtles

Piovano, Susanna; Farcomeni, Alessio; Giacoma, Cristina

doi:10.2989/1814232x.2012.675126

Cited by 7 publications

(6 citation statements)

References 37 publications

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“…There have been conflicting findings on the effect of using fish vs. squid species for bait on catch rates of individual teleost and elasmobranch species, but relatively consistent findings that using small fish species for bait reduces sea turtle catch rates relative to using squid for bait (Broadhurst and Hazin, ; Watson et al ., ; Mejuto et al ., ; Yokota et al ., ; Coelho et al ., ; Foster et al ., ; Piovano et al ., ; Santos et al ., ; Amorim et al ., ; Clarke et al ., ). A few studies have observed that using fish instead of squid for bait significantly increased the proportion of some species of caught sharks that were deeply hooked, with the opposite effect for swordfish (Broadhurst and Hazin, ; Watson et al ., ; Epperly et al ., ).…”

Section: Discussionmentioning

confidence: 99%

Standardized catch and survival rates, and effect of a ban on shark retention, Palau pelagic longline fishery

Gilman

Chaloupka

Merrifield³

et al. 2015

Aquatic Conservation

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1. Pelagic longline fisheries affect both market and vulnerable bycatch species and can have broad effects on community structure and processes.2. Observer data from the Palau longline fishery were analysed to identify opportunities to mitigate vulnerable species bycatch, determine temporal trends in local abundance, and assess changes following a ban on shark retention and wire leaders. Catch and haulback condition data for bigeye and yellowfin tunas, blue and silky sharks and pelagic stingrays were fitted to standardized catch and survival rate models.3. The fishery caught silky and blue sharks, olive ridley sea turtles and other species of conservation concern. 4. Changing from shallow sets to deep daytime sets might reduce shark and sea turtle catch rates but increase turtle haulback mortality rates, maintain economically viable tuna catch rates, but increase catch rates of pelagic stingrays, a lower conservation concern than main caught species of sharks and turtles. 5. Focusing fishing effort during the middle of the calendar year would maximize yellowfin tuna and minimize silky shark standardized catch rates, but maximize blue shark catch rates. 6. A large decline in shark fishing mortality rate very likely occurred following a ban on shark retention and wire leaders. This was due to large reductions in the nominal shark catch rate and shark retention, partially offset by decreases in the shark haulback survival rate and pre-catch survival rate. Significantly higher blue shark and lower pelagic stingray nominal catch rates occurred on wire vs. monofilament leaders. Significantly higher blue shark and lower yellowfin tuna nominal catch rates occurred on sets using shallow 'shark lines'. It is a research priority to compare the probability of shark pre-catch survival after escaping from monofilament leaders with an ingested hook and trailing line to the survival probability when captured on wire leaders.

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Section: Discussionmentioning

confidence: 99%

Standardized catch and survival rates, and effect of a ban on shark retention, Palau pelagic longline fishery

Gilman

Chaloupka

Merrifield³

et al. 2015

Aquatic Conservation

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“…These are possible factors explaining differences in catch rates between pelagic species and between sizes of individual pelagic species on fish versus squid for bait (Lokkeborg and Bjordal 1992;Broadhurst and Hazin 2001;Ward and Myers 2007;Yokota et al 2009). Hardshelled turtles may prefer squid to finfish due to natural chemical attractants present in squid (Piovano et al 2004(Piovano et al , 2012.…”

Section: Bait Typementioning

confidence: 99%

Review of effects of pelagic longline hook and bait type on sea turtle catch rate, anatomical hooking position and at-vessel mortality rate

Gilman

Huang

2016

Rev Fish Biol Fisheries

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Review of effects of pelagic longline hook and bait type on sea turtle catch rate, anatomical hooking position and at-vessel mortality rate WCPFC-SC13-2017/ EB-IP-01Gilman, E 1 . and H-W. Abstract Bycatch in pelagic longline fisheries is one of the most serious threats to some sea turtle populations. Hook shape, hook minimum width and bait type have been the focus of research and management measures to mitigate problematic bycatch of vulnerable taxa. To assess the current state of knowledge and progress over the past decade, we reviewed findings on the effects of hook and bait type on pelagic longline sea turtle catch rates, anatomical hooking position and at-vessel mortality. Fish versus squid for bait lowered catch rates of leatherback sea turtles (Dermochelys coriacea) and individual species of hard shelled turtles. Fish bait also reduced hard-shelled turtle deep hooking. Wider circle hooks reduced both leatherback and hard-shelled turtle catch rates relative to narrower J and tuna hooks, and reduced the proportion of caught hard-shelled turtles that were deeply hooked. Wider circle hooks with fish bait reduced leatherback and hard-shelled turtle catch rates relative to narrower J and tuna hooks with squid bait. Wider versus narrower circle hooks reduced hard-shelled sea turtle catch rates and deep hooking. The mechanisms for hook and bait type effects on turtle interactions are reviewed. Research designed to assess single factor effects is needed, in particular for hook shape and minimum width, and for hook and bait effects on anatomical hooking position and survival rates. Fishery-specific and holistic assessments are needed to account for variability between fisheries in a bycatch mitigation method's commercial viability, relative risks to affected populations and possible conflicting effects on vulnerable taxa.

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“…In particular, since physical forcings are among the main drivers of zooplankton dispersal [91], geophonic components like wind intensity might indirectly inform sea turtles about the presence of macro-and mega-zooplankton brought to the coast by higher wind intensity. The use of sensory stimuli by hard-shell sea turtles to orient towards their food choice has been proven chemically [92][93][94] and visually [95][96][97], and might extend to the use of acoustic stimuli. Comparison between geophonies, the abundance of planktonic food, and sea turtle spatial behavior recorded via satellite tracking would help clarify the effect of wind intensity on sea turtle behavior.…”

Section: Discussionmentioning

confidence: 99%

Soundscape of green turtle foraging habitats in Fiji, South Pacific

et al. 2020

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The soundscape features of the marine environment provide crucial information about ecosystem health for many species, and they are defined by the local biological, geophysical, and anthropogenic components. In this study, we investigated the soundscape at green turtle neritic foraging habitats in Fiji, South Pacific, with the aims of characterizing the contribution of each component and of comparing the levels of acoustic pressure among sites with different abundances of sea turtles. Four sites were selected at two islands, and one hydrophone was deployed at each site. Generalized additive models highlighted that sound pressure levels (SPLs) at low frequencies (125-250 Hz) were especially affected by wind conditions, while at higher frequencies (>250 Hz) SPLs were mostly influenced by fish and crustacean acoustic activity. Higher abundances of green turtles were found at sites with the highest levels of SPLs and the highest number of acoustic emissions by fishes and crustaceans but were not related to maximum seagrass and macroalgae coverage, or the highest number of fish. The selected coastal habitats have negligible anthropogenic noise, thus this study informs physiological and behavioral studies of the acoustic signatures that sea turtles might target and provides a baseline against which potential impact of soundscape changes on sea turtle spatial abundance and distribution can be evaluated.

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Effects of chemicals from longline baits on the biting behaviour of loggerhead sea turtles

Cited by 7 publications

References 37 publications

Standardized catch and survival rates, and effect of a ban on shark retention, Palau pelagic longline fishery

Standardized catch and survival rates, and effect of a ban on shark retention, Palau pelagic longline fishery

Review of effects of pelagic longline hook and bait type on sea turtle catch rate, anatomical hooking position and at-vessel mortality rate

Soundscape of green turtle foraging habitats in Fiji, South Pacific

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