Post-release mortality, recovery, and stress physiology of blacknose sharks, Carcharhinus acronotus, in the Southeast U.S. recreational shark fishery

Knotek, Ryan J.; Frazier, Bryan S.; Daly-Engel, T.S.; White, Connor F.; Barry, S.N.; Cave, E.J.; Whitney, Nicholas M.

doi:10.1016/j.fishres.2022.106406

Cited by 9 publications

(8 citation statements)

References 61 publications

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“…The other major discrepancy between boat-based and shore-based angling is the increased temperatures sharks experience when caught and landed in the shallow, warm surf. Consistent with other studies that explore the effects of temperature on stress and mortality [16,23,[49][50][51][52][53][54], our study suggests that increased temperatures significantly impact the ability of some species to recover and survive following capture and release. Statistical comparison of environmental and capture covariates between blacktip sharks that survived and those that died revealed moribund blacktip sharks experienced significantly higher temperatures both in the initial 10 minutes following release and for the entire time at liberty until mortality occurred compared with those that did survive.…”

Section: Plos Onesupporting

confidence: 91%

“…Risk of mortality can also be exacerbated when certain environmental conditions prevent an efficient and effective recovery from the stress of capture, and here we support a large body of work pointing towards increased temperatures as a significant factor reducing survival [16,23,[49][50][51][52][53][54]. Many elasmobranch studies have demonstrated that the physiological stress and physical damage from capture and restraint may elicit biochemical responses that affect both short-and long-term fitness following release [4,[8][9][10][55][56][57].…”

Section: Discussionsupporting

confidence: 59%

“…Warmer water temperatures have been demonstrated to exacerbate the sublethal physiological disturbances experienced by elasmobranchs [ 16 , 23 , 53 ], resulting in hypoxia, reduced myocardial function, and acidosis [ 62 , 63 ] In two separate studies, [ 16 , 54 ] found that higher water temperatures intensified the stress response in blacktip sharks, resulting in substantially higher rates of PRM. For species that tend to fight harder when hooked, the increased oxygen demand in the face of hypoxic conditions due to higher temperatures leads to increased stress and risk of mortality [ 64 ].…”

Section: Discussionmentioning

confidence: 99%

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Variable post-release mortality in common shark species captured in Texas shore-based recreational fisheries

et al. 2023

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The practice of catch and release fishing is common among anglers but has been shown to cause unintended mortalities in some species. Current post-release mortality estimates used in coastal shark stock assessments are typically derived from boat-based shark fisheries, which differ from shore-based operations that expose sharks to potentially more stressful environmental and handling conditions. Recreational post-release mortality rates in shore-based fisheries must be quantified to improve stock assessment models and to create guidelines that protect species from overexploitation. Here, we partnered with experienced anglers acting as citizen scientists to deploy pop-up satellite archival transmitting tags (PSAT, n = 22) and acceleration data loggers (ADLs, n = 22). on four commonly caught sharks including the blacktip shark (Carcharhinus limbatus, n = 11), bull shark (Carcharhinus leucas, n = 14), tiger shark (Galeocerdo cuvier, n = 6), and great hammerheads (Sphyrna mokarran, n = 2). Mortality occurred within minutes to hours post-release. If evidence of mortality occurred after normal diving behavior had been re-established for 10 days, then the mortality was considered natural and not related to the catch-and-release process. Post-release mortality estimates ranged from 0% for bull and tiger sharks to 45.5% for blacktip sharks. Of the two great hammerheads, one died within 30 minutes post-release while the other exhibited mortality characteristics 14 days after release. Moribund blacktip sharks experienced on average 3.4–4.9°C warmer water compared with survivors. Recovery periods were estimated for survivors of each species and were highly variable, differing based on duration of tag deployment. High variability in responses to capture and release between species demonstrates the need for species-specific assessments of post-release mortality in shore-based recreational fisheries.

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Section: Plos Onesupporting

confidence: 91%

Section: Discussionsupporting

confidence: 59%

Section: Discussionmentioning

confidence: 99%

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Variable post-release mortality in common shark species captured in Texas shore-based recreational fisheries

et al. 2023

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“…Any geolocator deployment comes with inherent risks for the animal's wellbeing, and deployment protocols with the smallest risks should be developed [16]. Therefore, from an ethical standpoint, a reduced handling time of the study animal, which was shown to increase the release condition and subsequent survival of on-board tagged blacknose sharks, Carcharhinus acronotus [10], is desirable independently of the species, and the least stressful deployment protocol must be chosen. We hope that our drill attachment can be used by other scientists and that it encourages the development of drill attachments for other type of geolocators as well.…”

Section: Discussionmentioning

confidence: 99%

“…However, great and scalloped hammerheads are listed as Critically Endangered on the IUCN red list [7,8] and both species would benefit from more fine-scale movement data, such as those generated by fin-mounted satellite-linked geolocators, allowing the discussion of more adequate conservation management measures [9]. To minimize the risks of detrimental effects during tagging activities, any sharks, but especially sharks with a fast lactate build-up and low stress tolerance, such as great and scalloped hammerheads, should, therefore, be brought to the boat and geolocators attached as fast as possible to reduce the probability of mortality [10].…”

Section: Introductionmentioning

confidence: 99%

Development and validation of a drill attachment for faster and safer deployments of fin-mounted geolocators in large-bodied sharks

et al. 2022

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Fin-mounted geolocators are widely used in marine studies to track animal movements and to design informed management strategies. However, the deployment protocols of such geolocators, which normally consist of drilling one to multiple holes using a template, can be challenging, and depending on the animal’s stress physiology and ocean conditions, speed and accuracy may be crucial. Here, we present the plans for a drill attachment allowing the template-free drilling of up to four holes simultaneously for a faster, more accurate and safer deployment of fin-mounted geolocators. The drill attachment was successfully tested on four great and two scalloped hammerheads, Sphyrna mokarran and Sphyrna lewini, which were all tagged with 4-bolt Smart Position and Temperature (SPOT) tags. The time required to secure the geolocators, from drill alignment to the complete fastening of the last bolt, ranged from 68 to 85 s (78.2 ± 10.9 s, mean ± SD). The new drill attachment further allowed the successful tagging of a great hammerhead alongside a research vessel in rough seas that would have made the deployment using traditional protocols more challenging. Simultaneously drilling four holes reduces the need to keep the animal’s fin steady for an extended period of time and thus makes the deployment of fin-mounted geolocators less dependent on the animal’s behavior and the weather conditions. As such, the 4-hole drill attachment makes the mounting process faster and more reliable and should reduce the stress experienced by the animal.

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Factors influencing the at‐haulback mortality of striped marlin Tetrapturus audax caught by tuna longline fishery in the western Indian Ocean

Li,

Wang,

Guo

et al. 2024

Aquatic Conservation

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Striped marlin (Tetrapturus audax) is an oceanic pelagic migratory fish. The stock status of striped marlin in the Indian Ocean is now considered to be overfished and subject to overfishing. Quantifying the level of at‐haulback mortality caused by longline fisheries for tuna and tuna‐like species is critical to reducing fishing pressure and protecting the fate of billfish stocks. This study was based on data from 2482 longline fishing operations recorded by Chinese observers in the western Indian Ocean from 2012 to 2019. The dataset includes information on the survival status of 774 striped marlin and their corresponding details. We used a generalized linear model (GLM) to analyse the level of at‐haulback mortality and its potential influencing factors. The results indicate that the distribution of 774 striped marlin had a lower jaw‐fork length (LJFL) range from 130 to 220 cm, and 51.5% of the specimens died at the time of haul‐back. The GLM model revealed that quarter, sea‐surface temperature (SST), hook type, LJFL, chlorophyll (CHL) and longitude had significant effects on at‐haulback condition when the fish were retrieved on board, with the quarter and sea surface temperature having the most significant effects. The interaction term between hook type and LJFL also had a significant effect on at‐haulback mortality, with the model predictions showing that mortality increased with LJFL when using circle hooks but decreased when using Japanese tuna hooks. There has been limited observational analysis of hooking mortality rates for striped marlin, and the present study may provide an important reference for the conservation and management of striped marlin stocks in the Indian Ocean.

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Post-release mortality, recovery, and stress physiology of blacknose sharks, Carcharhinus acronotus, in the Southeast U.S. recreational shark fishery

Cited by 9 publications

References 61 publications

Variable post-release mortality in common shark species captured in Texas shore-based recreational fisheries

Variable post-release mortality in common shark species captured in Texas shore-based recreational fisheries

Development and validation of a drill attachment for faster and safer deployments of fin-mounted geolocators in large-bodied sharks

Factors influencing the at‐haulback mortality of striped marlin Tetrapturus audax caught by tuna longline fishery in the western Indian Ocean

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