- Email: [email protected]
Integrating the findings from this special issue and suggestions for future conservation efforts – A brief synopsis
Ocean & Coastal Management 97 (2014) 58e60
Contents lists available at ScienceDirect
Ocean & Coastal Management journal homepage: www.elsevier.com/locate/ocecoaman
Integrating the findings from this special issue and suggestions for future conservation efforts e A brief synopsis Craig P. O’Connell a, *, Victor N. de Jonge b a b
O’Seas Conservation Foundation, Bronx, NY 10463, USA Institute of Estuarine & Coastal Studies, The University of Hull, Hull HU6 7RX, United Kingdom
a r t i c l e i n f o
a b s t r a c t
Article history: Available online 24 June 2014
The populations of several elasmobranch species have experienced a marked decline over the past several decades. Such declines may be attributed to the unsustainable harvest of these animals in combination with their K-selected life-history characteristics. To help reduce this mortality typically associated with commercial fisheries and beach nets, scientists have employed the use of electrosensory and chemical stimuli as elasmobranch deterrents. This paper describes the findings from several studies that assess elasmobranch deterrent efficacy, briefly integrates these findings, and provides useful insight for future conservation approaches. © 2014 Elsevier Ltd. All rights reserved.
1. Introduction Fisheries and beach nets are major contributors to elasmobranch (i.e. shark, skates and rays) decline (Bonfil, 1994; Baum et al., 2003; Baum and Myers, 2004; Cliff and Dudley, 1992; Dudley, 1997; Shepherd and Myers, 2005). Elasmobranchs are K-selected (i.e. slow growth rate, late maturity, and low fecundity), therefore the likelihood of population rebound in response to their unsustainable harvest is minimal if the present mortality rates continue (Pratt and Casey, 1990). As an example, annual global assessments estimate that an average of 100 million sharks are killed due to a variety of legal and illegal fishing practices (Worm et al., 2013). Furthermore, average exploitation rates exceed those of average rebound rates (Worm et al., 2013) making it difficult for populations to recover. Since many shark species play a top-down predatory role within their respective ecosystems, population declines at such high levels may have substantial ecological consequences (Myers et al., 2007; Heithaus et al., 2008; Burkholder et al., 2013). For example, Burkholder et al. (2013) demonstrated the importance of large predatory sharks within Shark Bay, Australia. The findings suggested the existence of a unique trophic relationship where the presence of tiger sharks (Galeocerdo cuvier) can directly influence the distribution of two grazer species, dugong (Dugong dugon) and green sea turtles (Chelonia mydas), which further influences the
density of seagrass species (Cymodocea angustata and Halodule uninervis). In response to elasmobranch population decline, several management plans have been instituted that: prohibit the retention of certain species, implement quotas and size regulations, in addition to a variety of other measures that aim to reduce landings/catch ratios. However, many elasmobranchs are highly migratory and often have transboundary distributions (Campana et al., 2006; Hammerschlag et al., 2011) and therefore, besides federal, regional or state management plans, international cooperation is essential for proper stock assessment and management (Musick et al., 2000). During this cooperation, the progression of population-related information typically yields the development of new laws, management techniques, and policies that sometimes originate at the international level (e.g. Convention on International Trade in Endangered Species of Wild Fauna and Flora e CITES and International Commission for the Conservation of Atlantic Tunas e ICCAT). However, more commonly these measures originate at the federal level (e.g. National Marine Fisheries Service e NMFS), and are then adopted at the regional level (e.g. Atlantic States Marine Fisheries Commission e ASMFC) and state levels (e.g. Massachusetts Division of Marine Fisheries).
2. Several conservation engineering approaches to Elasmobranch management * Corresponding author. E-mail address: [email protected] (C.P. O’Connell). http://dx.doi.org/10.1016/j.ocecoaman.2014.05.022 0964-5691/© 2014 Elsevier Ltd. All rights reserved.
Although management plans often impart strict rules and regulations for both recreational and commercial fisheries, substantial
C.P. O’Connell, V.N. de Jonge / Ocean & Coastal Management 97 (2014) 58e60
elasmobranch bycatch still occurs (Worm et al., 2013). To address this bycatch issue and the directed elasmobranch capture in beach nets, scientists have commenced experimentation with conservation engineering technologies, including electrosensory (e.g. permanent magnets or electropositive metals) and chemical stimuli (O’Connell et al., 2010, 2011; Rigg et al., 2009; Robbins et al., 2011; Stroud, 2008). This special issue explored the efficacy and utility of these technologies. First, both laboratory and field analyses were conducted which examined the effects of permanent magnets on a variety of elasmobranch and teleost species, and how both environmental and biological variables may alter electrosensory repellent efficacy. Results from the small-scale barrier studies demonstrate that behavior towards magnetic stimuli varied on a speciesspecific basis, where a visual stimulus was sufficient to elicit significant changes in white shark (Carcharodon carcharias) swimming behavior whereas the combination of visual and magnetic stimuli were needed to significantly alter bull shark (Carcharhinus lecuas) swimming behavior. These findings illustrate the species-specificity of elasmobranch responses to electrosensory stimuli and suggest how behavioral ecology of each species may play a role in repellent effectiveness. Although these studies were often simplistic in their nature (e.g. barriers were often only several meters in length), these studies illustrate that future conservation engineering research is warranted. However, to understand true technological potential, future studies may want to focus more heavily on the exclusion capabilities of magnetic barriers and how these barriers could be directly applied in conservation engineering applications should they exhibit future promise. Secondly, this special issue described and evaluated the efficacy of a newly developed shark deterrent hook, the SMART (Selective Magnetic and Repellent-Treated) hook on spiny dogfish (Squalus acanthias) capture. This study illustrated that the SMART hook possessed deterrent capabilities; however, the continual replacement of Mg2þ metal served as an inherent difficulty that deemed the hooks impractical for a fast-paced longline fishery. But, with the observed catch reduction of S. acanthias, the utilization of these hooks in a small-scale hook-and-line fishery may be a feasible option for future research. Thirdly, this special issue presented findings pertaining to elasmobranch-derived semiochemicals. The scientific understanding of these newly derived chemicals is in its infancy, but the present findings illustrate promise in elasmobranch-specific repellency and thus future research is warranted. It is essential to determine key components of these chemicals and their potential effect on the environment and exposed animals, their influence on heterospecifics (e.g. other elasmobranchs within or from another trophic level), and their potential for conservation engineering applications.
59
gear deployment and retrieval processes. In a large-scale fishery, such issues would prohibit “normal” fishing practices that would not only directly impact fishing capabilities but also lead to economic strains. Secondly, placing a magnet adjacent to a fishing hook may reduce shark bycatch (for certain species); however, these magnets may also serve as a large visual stimulus and concurrently a “deterrent” to target species (e.g. teleosts). Therefore, tradeoffs between elasmobranch bycatch and target capture should be considered when developing future conservation technologies. Conducting preliminary or proof-of-concept research is crucial for field progression and serves as the baseline for technological evolution that may contribute to the development of future successful conservation strategies. For example, due to O’Connell et al. (2011), it was discovered that fishing hooks could be magnetized and that the associated magnetic flux was capable of eliciting deterrent responses in several elasmobranch species (O’Connell, Pers. Obs.). This finding led to the development of the SMART hook. Based on the findings from this special issue, the SMART hook has demonstrated promise and although a modification in the selected metal type may be required for future implementation to maximize practicality, this study helped provide suggestions for future research and technological developments. 4. Conclusion The studies within this special issue collectively demonstrate new concepts in elasmobranch repellent research and also provide insight into favorable conditions and limitations that may yield more consistent and successful future implementation of electrosensory repellents. These imperatives coincide with the need to integrate environmental and biological factors into future experimental analyses and how these factors may maximize success in future applications and thus contribute to marine sustainability (Fath, in press). Furthermore, these studies represent an advancement of a new field of conservation engineering research and provide suggestions for future experimental directions. Lastly, with the progression of time, humans are having an increasingly negative impact on both terrestrial and aquatic ecosystems in m any regions. In addition, the continued development associated with human populations is often considered as societal evolution; however, this development is often leading to environmental degradation and should rather be viewed as human devolution. Therefore, the conservation efforts presented in this special issue represent means of initiative that should be adopted to help combat the deleterious effects humans are having on the delicate balance that exists within the marine realm. References
3. Future considerations Beyond basic behavioral assessments regarding the efficacy of conservation technologies, it is imperative that logistical feasibility and economic constraints are considered. For example, a previous study tested the effects of permanent magnets on hook-and-line and longline fishing gears (O’Connell et al., 2011). Although magnets had a significant influence on the catch rates of several elasmobranch species, it was imperative to modify the conservation approach to maximize the logistical practicality of technological integration for several reasons. First, substantial quantities of magnets in close proximity to fishing hooks can lead to logistical issues pertaining to gear entanglement which may prolong both
Baum, J.K., Myers, R.A., 2004. Shifting baselines and the decline of pelagic sharks in the Gulf of Mexico. Ecol. Lett. 7, 135e145. Baum, J.K., Myers, R.A., Kehler, D.G., Worm, B., Harley, S.J., Doherty, P.A., 2003. Collapse and conservation of shark populations in the Northwest Atlantic. Science 299, 389e392. Bonfil, R., 1994. Overview of World Elasmobranch Fisheries. FAO, Rome, p. 119. FAO Fish. Tech. Paper No. 341. Burkholder, D.A., Heithaus, M.R., Fourqurean, J.W., Wirsing, A., Dill, L.M., 2013. Patterns of top-down control in a seagrass ecosystem: could a roving apex predator induce a behaviour-mediated trophic cascade? J. Anim. Ecol. doi: 10.1111/1365e2656.12097. Campana, S.E., Marks, L., Joyce, W., Kohler, N.E., 2006. Effects of recreational and commercial fishing on blue sharks (Prionace glauca) in Atlantic Canada, with inferences on the North Atlantic population. Can. J. Fish. Aquat. Sci. 63 (3), 670e682. Cliff, G., Dudley, S.F.J., 1992. Protection against shark attack in South Africa. Aust. J. Mar. Fresh. Res. 43, 263e272.
60
C.P. O’Connell, V.N. de Jonge / Ocean & Coastal Management 97 (2014) 58e60
Dudley, S.F.J., 1997. A comparison of the shark control programs of New South Wales and Queensland (Australia) and KwaZulu-Natal (South Africa). Ocean. Coast. Manag. 34, 1e27. Fath, B.D., 2014. Quantifying economic and ecological sustainability. Ocean. Coast. Manag. in press. Hammerschlag, N., Gallagher, A.J., Lazarre, D.M., Slonim, C., 2011. Range extension of the Endangered great hammerhead shark Sphyrna mokarran in the Northwest Atlantic: preliminary data and significance for conservation. Endanger. Species Res. 13, 111e116. Heithaus, M.R., Frid, A., Wirsing, A.J., Worm, B., 2008. Predicting ecological consequences of marine top predator declines. Trends Ecol. Evol. 23 (4), 202e210. Musick, J.A., Burgess, G., Cailliet, G., Camhi, M., Fordham, S., 2000. Management of sharks and their relatives (Elasmobranchii). Fisheries 25 (3), 9e13. Myers, R.A., Baum, J.K., Shepherd, T.D., Powers, S.P., Peterson, C.H., 2007. Cascading effects of the loss of apex predatory sharks from a coastal ocean. Science 315, 1846e1852. O’Connell, C.P., Abel, D.C., Rice, P.H., Stroud, E.M., Simuro, N.C., 2010. Responses of the southern stingray (Dasyatis americana) and the nurse shark (Ginglymostoma cirratum) to permanent magnets. Mar. Freshw. Behav. Phys. 43, 63e73. O’Connell, C.P., Abel, D.C., Stroud, E.M., 2011. Analysis of permanent magnets as elasmobranch bycatch reduction devices in hook-and-line and longline trials. Fish. Bull. 109 (4), 394e401.
Pratt Jr., H.L., Casey, J.G., 1990. Shark reproductive strategies as a limiting factor in directed fisheries, with a review of Holden’s method of estimating growth parameters. In: Pratt Jr., H.L., Gruber, S.H., Taniuchi, T. (Eds.), Elasmobranchs as Living Resources: Advances in the Biology, Ecology, and Systematics, and the Status of the Fisheries. U.S. Dep. Commer., pp. 97e109. NOAA Tech. Rep. NMFS 90. Rigg, D.P., Peverell, S.C., Hearndon, M., Seymour, J.E., 2009. Do elasmobranch reactions to magnetic fields in water show promise for bycatch mitigation? Mar. Freshw. Res. 60, 942e948. Robbins, W.D., Peddemors, V.M., Kennelly, S.J., 2011. Assessment of permanent magnets and electropositive metals to reduce the line-based capture of Galapagos sharks, Carcharhinus galapagensis. Fish. Res. 109, 100e106. Shepherd, T.D., Myers, R.A., 2005. Direct and indirect fishery effects on small coastal elasmobranchs in the northern Gulf of Mexico. Ecol. Lett. 8, 1095e1104. Stroud, E.M., 2008. Chemical shark repellents: identifying the actives and controlling their release. In: Swimmer, Y., Wang, J.H., McNaughton, L. (Eds.), Shark Deterrent and Incidental Capture Workshop, 10e11 April 2008. US Department of Commerce, pp. 43e46. NOAA Technical Memorandum NOAA-TM-NMFSPIFSC-16. 72 (pp.). Worm, B., Davis, B., Kettemer, L., Ward-Paige, C.A., et al., 2013. Global catches, exploitation rates, and rebuilding options for sharks. Mar. Pol. 40, 194e204.
Contents lists available at ScienceDirect
Ocean & Coastal Management journal homepage: www.elsevier.com/locate/ocecoaman
Integrating the findings from this special issue and suggestions for future conservation efforts e A brief synopsis Craig P. O’Connell a, *, Victor N. de Jonge b a b
O’Seas Conservation Foundation, Bronx, NY 10463, USA Institute of Estuarine & Coastal Studies, The University of Hull, Hull HU6 7RX, United Kingdom
a r t i c l e i n f o
a b s t r a c t
Article history: Available online 24 June 2014
The populations of several elasmobranch species have experienced a marked decline over the past several decades. Such declines may be attributed to the unsustainable harvest of these animals in combination with their K-selected life-history characteristics. To help reduce this mortality typically associated with commercial fisheries and beach nets, scientists have employed the use of electrosensory and chemical stimuli as elasmobranch deterrents. This paper describes the findings from several studies that assess elasmobranch deterrent efficacy, briefly integrates these findings, and provides useful insight for future conservation approaches. © 2014 Elsevier Ltd. All rights reserved.
1. Introduction Fisheries and beach nets are major contributors to elasmobranch (i.e. shark, skates and rays) decline (Bonfil, 1994; Baum et al., 2003; Baum and Myers, 2004; Cliff and Dudley, 1992; Dudley, 1997; Shepherd and Myers, 2005). Elasmobranchs are K-selected (i.e. slow growth rate, late maturity, and low fecundity), therefore the likelihood of population rebound in response to their unsustainable harvest is minimal if the present mortality rates continue (Pratt and Casey, 1990). As an example, annual global assessments estimate that an average of 100 million sharks are killed due to a variety of legal and illegal fishing practices (Worm et al., 2013). Furthermore, average exploitation rates exceed those of average rebound rates (Worm et al., 2013) making it difficult for populations to recover. Since many shark species play a top-down predatory role within their respective ecosystems, population declines at such high levels may have substantial ecological consequences (Myers et al., 2007; Heithaus et al., 2008; Burkholder et al., 2013). For example, Burkholder et al. (2013) demonstrated the importance of large predatory sharks within Shark Bay, Australia. The findings suggested the existence of a unique trophic relationship where the presence of tiger sharks (Galeocerdo cuvier) can directly influence the distribution of two grazer species, dugong (Dugong dugon) and green sea turtles (Chelonia mydas), which further influences the
density of seagrass species (Cymodocea angustata and Halodule uninervis). In response to elasmobranch population decline, several management plans have been instituted that: prohibit the retention of certain species, implement quotas and size regulations, in addition to a variety of other measures that aim to reduce landings/catch ratios. However, many elasmobranchs are highly migratory and often have transboundary distributions (Campana et al., 2006; Hammerschlag et al., 2011) and therefore, besides federal, regional or state management plans, international cooperation is essential for proper stock assessment and management (Musick et al., 2000). During this cooperation, the progression of population-related information typically yields the development of new laws, management techniques, and policies that sometimes originate at the international level (e.g. Convention on International Trade in Endangered Species of Wild Fauna and Flora e CITES and International Commission for the Conservation of Atlantic Tunas e ICCAT). However, more commonly these measures originate at the federal level (e.g. National Marine Fisheries Service e NMFS), and are then adopted at the regional level (e.g. Atlantic States Marine Fisheries Commission e ASMFC) and state levels (e.g. Massachusetts Division of Marine Fisheries).
2. Several conservation engineering approaches to Elasmobranch management * Corresponding author. E-mail address: [email protected] (C.P. O’Connell). http://dx.doi.org/10.1016/j.ocecoaman.2014.05.022 0964-5691/© 2014 Elsevier Ltd. All rights reserved.
Although management plans often impart strict rules and regulations for both recreational and commercial fisheries, substantial
C.P. O’Connell, V.N. de Jonge / Ocean & Coastal Management 97 (2014) 58e60
elasmobranch bycatch still occurs (Worm et al., 2013). To address this bycatch issue and the directed elasmobranch capture in beach nets, scientists have commenced experimentation with conservation engineering technologies, including electrosensory (e.g. permanent magnets or electropositive metals) and chemical stimuli (O’Connell et al., 2010, 2011; Rigg et al., 2009; Robbins et al., 2011; Stroud, 2008). This special issue explored the efficacy and utility of these technologies. First, both laboratory and field analyses were conducted which examined the effects of permanent magnets on a variety of elasmobranch and teleost species, and how both environmental and biological variables may alter electrosensory repellent efficacy. Results from the small-scale barrier studies demonstrate that behavior towards magnetic stimuli varied on a speciesspecific basis, where a visual stimulus was sufficient to elicit significant changes in white shark (Carcharodon carcharias) swimming behavior whereas the combination of visual and magnetic stimuli were needed to significantly alter bull shark (Carcharhinus lecuas) swimming behavior. These findings illustrate the species-specificity of elasmobranch responses to electrosensory stimuli and suggest how behavioral ecology of each species may play a role in repellent effectiveness. Although these studies were often simplistic in their nature (e.g. barriers were often only several meters in length), these studies illustrate that future conservation engineering research is warranted. However, to understand true technological potential, future studies may want to focus more heavily on the exclusion capabilities of magnetic barriers and how these barriers could be directly applied in conservation engineering applications should they exhibit future promise. Secondly, this special issue described and evaluated the efficacy of a newly developed shark deterrent hook, the SMART (Selective Magnetic and Repellent-Treated) hook on spiny dogfish (Squalus acanthias) capture. This study illustrated that the SMART hook possessed deterrent capabilities; however, the continual replacement of Mg2þ metal served as an inherent difficulty that deemed the hooks impractical for a fast-paced longline fishery. But, with the observed catch reduction of S. acanthias, the utilization of these hooks in a small-scale hook-and-line fishery may be a feasible option for future research. Thirdly, this special issue presented findings pertaining to elasmobranch-derived semiochemicals. The scientific understanding of these newly derived chemicals is in its infancy, but the present findings illustrate promise in elasmobranch-specific repellency and thus future research is warranted. It is essential to determine key components of these chemicals and their potential effect on the environment and exposed animals, their influence on heterospecifics (e.g. other elasmobranchs within or from another trophic level), and their potential for conservation engineering applications.
59
gear deployment and retrieval processes. In a large-scale fishery, such issues would prohibit “normal” fishing practices that would not only directly impact fishing capabilities but also lead to economic strains. Secondly, placing a magnet adjacent to a fishing hook may reduce shark bycatch (for certain species); however, these magnets may also serve as a large visual stimulus and concurrently a “deterrent” to target species (e.g. teleosts). Therefore, tradeoffs between elasmobranch bycatch and target capture should be considered when developing future conservation technologies. Conducting preliminary or proof-of-concept research is crucial for field progression and serves as the baseline for technological evolution that may contribute to the development of future successful conservation strategies. For example, due to O’Connell et al. (2011), it was discovered that fishing hooks could be magnetized and that the associated magnetic flux was capable of eliciting deterrent responses in several elasmobranch species (O’Connell, Pers. Obs.). This finding led to the development of the SMART hook. Based on the findings from this special issue, the SMART hook has demonstrated promise and although a modification in the selected metal type may be required for future implementation to maximize practicality, this study helped provide suggestions for future research and technological developments. 4. Conclusion The studies within this special issue collectively demonstrate new concepts in elasmobranch repellent research and also provide insight into favorable conditions and limitations that may yield more consistent and successful future implementation of electrosensory repellents. These imperatives coincide with the need to integrate environmental and biological factors into future experimental analyses and how these factors may maximize success in future applications and thus contribute to marine sustainability (Fath, in press). Furthermore, these studies represent an advancement of a new field of conservation engineering research and provide suggestions for future experimental directions. Lastly, with the progression of time, humans are having an increasingly negative impact on both terrestrial and aquatic ecosystems in m any regions. In addition, the continued development associated with human populations is often considered as societal evolution; however, this development is often leading to environmental degradation and should rather be viewed as human devolution. Therefore, the conservation efforts presented in this special issue represent means of initiative that should be adopted to help combat the deleterious effects humans are having on the delicate balance that exists within the marine realm. References
3. Future considerations Beyond basic behavioral assessments regarding the efficacy of conservation technologies, it is imperative that logistical feasibility and economic constraints are considered. For example, a previous study tested the effects of permanent magnets on hook-and-line and longline fishing gears (O’Connell et al., 2011). Although magnets had a significant influence on the catch rates of several elasmobranch species, it was imperative to modify the conservation approach to maximize the logistical practicality of technological integration for several reasons. First, substantial quantities of magnets in close proximity to fishing hooks can lead to logistical issues pertaining to gear entanglement which may prolong both
Baum, J.K., Myers, R.A., 2004. Shifting baselines and the decline of pelagic sharks in the Gulf of Mexico. Ecol. Lett. 7, 135e145. Baum, J.K., Myers, R.A., Kehler, D.G., Worm, B., Harley, S.J., Doherty, P.A., 2003. Collapse and conservation of shark populations in the Northwest Atlantic. Science 299, 389e392. Bonfil, R., 1994. Overview of World Elasmobranch Fisheries. FAO, Rome, p. 119. FAO Fish. Tech. Paper No. 341. Burkholder, D.A., Heithaus, M.R., Fourqurean, J.W., Wirsing, A., Dill, L.M., 2013. Patterns of top-down control in a seagrass ecosystem: could a roving apex predator induce a behaviour-mediated trophic cascade? J. Anim. Ecol. doi: 10.1111/1365e2656.12097. Campana, S.E., Marks, L., Joyce, W., Kohler, N.E., 2006. Effects of recreational and commercial fishing on blue sharks (Prionace glauca) in Atlantic Canada, with inferences on the North Atlantic population. Can. J. Fish. Aquat. Sci. 63 (3), 670e682. Cliff, G., Dudley, S.F.J., 1992. Protection against shark attack in South Africa. Aust. J. Mar. Fresh. Res. 43, 263e272.
60
C.P. O’Connell, V.N. de Jonge / Ocean & Coastal Management 97 (2014) 58e60
Dudley, S.F.J., 1997. A comparison of the shark control programs of New South Wales and Queensland (Australia) and KwaZulu-Natal (South Africa). Ocean. Coast. Manag. 34, 1e27. Fath, B.D., 2014. Quantifying economic and ecological sustainability. Ocean. Coast. Manag. in press. Hammerschlag, N., Gallagher, A.J., Lazarre, D.M., Slonim, C., 2011. Range extension of the Endangered great hammerhead shark Sphyrna mokarran in the Northwest Atlantic: preliminary data and significance for conservation. Endanger. Species Res. 13, 111e116. Heithaus, M.R., Frid, A., Wirsing, A.J., Worm, B., 2008. Predicting ecological consequences of marine top predator declines. Trends Ecol. Evol. 23 (4), 202e210. Musick, J.A., Burgess, G., Cailliet, G., Camhi, M., Fordham, S., 2000. Management of sharks and their relatives (Elasmobranchii). Fisheries 25 (3), 9e13. Myers, R.A., Baum, J.K., Shepherd, T.D., Powers, S.P., Peterson, C.H., 2007. Cascading effects of the loss of apex predatory sharks from a coastal ocean. Science 315, 1846e1852. O’Connell, C.P., Abel, D.C., Rice, P.H., Stroud, E.M., Simuro, N.C., 2010. Responses of the southern stingray (Dasyatis americana) and the nurse shark (Ginglymostoma cirratum) to permanent magnets. Mar. Freshw. Behav. Phys. 43, 63e73. O’Connell, C.P., Abel, D.C., Stroud, E.M., 2011. Analysis of permanent magnets as elasmobranch bycatch reduction devices in hook-and-line and longline trials. Fish. Bull. 109 (4), 394e401.
Pratt Jr., H.L., Casey, J.G., 1990. Shark reproductive strategies as a limiting factor in directed fisheries, with a review of Holden’s method of estimating growth parameters. In: Pratt Jr., H.L., Gruber, S.H., Taniuchi, T. (Eds.), Elasmobranchs as Living Resources: Advances in the Biology, Ecology, and Systematics, and the Status of the Fisheries. U.S. Dep. Commer., pp. 97e109. NOAA Tech. Rep. NMFS 90. Rigg, D.P., Peverell, S.C., Hearndon, M., Seymour, J.E., 2009. Do elasmobranch reactions to magnetic fields in water show promise for bycatch mitigation? Mar. Freshw. Res. 60, 942e948. Robbins, W.D., Peddemors, V.M., Kennelly, S.J., 2011. Assessment of permanent magnets and electropositive metals to reduce the line-based capture of Galapagos sharks, Carcharhinus galapagensis. Fish. Res. 109, 100e106. Shepherd, T.D., Myers, R.A., 2005. Direct and indirect fishery effects on small coastal elasmobranchs in the northern Gulf of Mexico. Ecol. Lett. 8, 1095e1104. Stroud, E.M., 2008. Chemical shark repellents: identifying the actives and controlling their release. In: Swimmer, Y., Wang, J.H., McNaughton, L. (Eds.), Shark Deterrent and Incidental Capture Workshop, 10e11 April 2008. US Department of Commerce, pp. 43e46. NOAA Technical Memorandum NOAA-TM-NMFSPIFSC-16. 72 (pp.). Worm, B., Davis, B., Kettemer, L., Ward-Paige, C.A., et al., 2013. Global catches, exploitation rates, and rebuilding options for sharks. Mar. Pol. 40, 194e204.