By-catch-associated demographics of two threatened seahorses from the south-east coast of India
Kannan Shalu A , Neelesh Dahanukar B C , Rajeev Raghavan
D F and Kutty Ranjeet E
+ Author Affiliations
- Author Affiliations
A School of Ocean Science and Technology, Kerala University of Fisheries and Ocean Studies (KUFOS), Kochi, 682 506, India.
B Biological Sciences, Indian Institute of Science Education and Research (IISER), Pune, 411 008, India.
C Laboratory of Systematics and Conservation, Zoo Outreach Organisation (ZOO), Coimbatore, 641 035, India.
D Department of Fisheries Resource Management, Kerala University of Fisheries and Ocean Studies (KUFOS), Kochi, 682 506, India.
E Department of Aquatic Environment Management, Kerala University of Fisheries and Ocean Studies (KUFOS), Kochi, 682 506, India.
F Corresponding author. Email: rajeevraq@hotmail.com
Marine and Freshwater Research 73(3) 343-350 https://doi.org/10.1071/MF21127
Submitted: 4 May 2021 Accepted: 6 October 2021 Published: 26 November 2021
Abstract
Seahorses comprise a charismatic, high-value and high conservation-concern group of fishes, whose demographics, including the dynamics of populations, are poorly studied. In this paper, we fill this key knowledge gap by determining the population dynamics of two threatened species, Hippocampus kuda and H. trimaculatus, from the south-east coast of India using samples encountered in trawl by-catch. Hippocampus kuda showed a comparatively greater asymptotic length, whereas H. trimaculatus had a greater growth coefficient and growth performance index. Further, H. trimaculatus showed two recruitment peaks (March/April and December) in a year, against a single peak (February) for H. kuda. An assessment of mortality rates (instantaneous total, natural and fishing) indicated a high vulnerability of the local population of both species to fishing pressure. Hippocampus kuda had a greater mean length at first capture than H. trimaculatus. Biomass-per-recruit analysis showed that the exploitation of H. kuda is closer to the exploitation rates under which stock will be reduced to half the unexploited biomass, suggesting their extreme vulnerability to overexploitation, even as ‘by-catch’. Demographic parameters of the two threatened seahorses indicated that even as ‘incidental catch’, these species are vulnerable to overfishing, and species-specific conservation guidelines need to be developed and their on-ground implementation and enforcement ensured.
Keywords: growth, length–weight relationship, by-catch, population dynamics, Syngnathidae.
References
Anju, C. V., Dahanukar, N., Sidharthan, A., Ranjeet, K., and Raghavan, R. (2019). Demographics of Lagocephalus inermis in the Arabian Sea unveils complex conservation challenges. Journal of Fish Biology 94, 187–190.| Demographics of Lagocephalus inermis in the Arabian Sea unveils complex conservation challenges.Crossref | GoogleScholarGoogle Scholar | 30565682PubMed |
Aylesworth, L. (2014). Spotted Seahorse Hippocampus kuda. In ‘The IUCN Red List of Threatened Species 2014’. e.T10075A16664386. (International Union for Conservation of Nature and Natural Resources.) Available at https://www.iucnredlist.org/species/10075/16664386 [Verified 27 April 2021]
Beverton, R. J. H., and Holt, S. J. (1966). ‘Manual of methods for fish stock assessment. Part II. Tables of yield functions’, FAO Fisheries Technical Paper number 38. (Food and Agriculture Organization of the United Nations, Rome, Italy.)
BOBLME (2015). Participatory management for conservation of seahorses in the Gulf of Mannar, south-east coast of India. BOBLME-2015- Ecology-58. Studia Marina Sinica 23, 83–93.
Cai, N., Xu, Q., Yu, F., Wu, X., and Sun, G. (1984). Studies on the reproduction of the seahorse Hippocampus trimaculatus. Studia Marina Sinica 23, 83–93.
Chellaiyan, D. (2011). Bionomics of a marine ornamental fish Hippocampus kuda (Bleeker 1852a) from Palk Strait Region south-east coast of India. Ph.D. Thesis, Bharathidasan University, Tiruchirapalli, Tamil Nadu, India.
Choo, C. K., and Liew, H. C. (2003). Spatial distribution, substrate assemblages and size composition of sea horses (Family Syngnathidae) in the coastal waters of Peninsular Journal of the Marine Biological Association of the United Kingdom 83, 271–276.
| Spatial distribution, substrate assemblages and size composition of sea horses (Family Syngnathidae) in the coastal waters of PeninsularCrossref | GoogleScholarGoogle Scholar |
Choo, C. K., and Liew, H. C. (2006). Morphological development and allometric growth patterns in the juvenile seahorse Hippocampus kuda, Bleeker. Journal of Fish Biology 69, 426–445.
| Morphological development and allometric growth patterns in the juvenile seahorse Hippocampus kuda, Bleeker.Crossref | GoogleScholarGoogle Scholar |
Csirke, J., Caddy, J. F., and Garcia, S. (1987). Methods of size-frequency analysis and their incorporation in programs for fish stock assessment in developing countries: FAO interest in receiving advice. In ‘Length-based methods in fisheries research. ICLARM Conference Proceedings 13’. (Eds D. Pauly and G. R. Morgan.) pp. 1–6. (International Center for Living Aquatic Resources Management: Manila, Philippines, and Kuwait Institute for Scientific Research: Safat, Kuwait.)
Foster, S. J., and Vincent, A. C. J. (2004). Life history and ecology of seahorses: implications for conservation and management. Journal of Fish Biology 65, 1–61.
| Life history and ecology of seahorses: implications for conservation and management.Crossref | GoogleScholarGoogle Scholar |
Foster, S. J., and Vincent, A. C. J. (2005). Enhancing sustainability of the international trade in seahorses with a single minimum size limit. Conservation Biology 19, 1044–1050.
| Enhancing sustainability of the international trade in seahorses with a single minimum size limit.Crossref | GoogleScholarGoogle Scholar |
Foster, S. J., Kuo, T. C., Wan, A. K. Y., and Vincent, A. C. J. (2019). Global seahorse trade defies export bans under CITES action and national legislation. Marine Policy 103, 33–41.
| Global seahorse trade defies export bans under CITES action and national legislation.Crossref | GoogleScholarGoogle Scholar |
Froese, R. (2006). Cube law, condition factor and weight–length relationships: history, meta‐analysis and recommendations. Journal of Applied Ichthyology 22, 241–253.
| Cube law, condition factor and weight–length relationships: history, meta‐analysis and recommendations.Crossref | GoogleScholarGoogle Scholar |
Gayanilo, F. C., Sparre, P., and Pauly, D. (2005). ‘The FAO–ICLARM stock assessment tools II (FiSAT II). User’s guide.’ Revised Version FAO Computerized Information Series (Fisheries): Vol. 8. (Food and Agricultural Organization: Rome, Italy.) Available at http://www.fao.org/3/y5997e/y5997e00.htm
Giles, B. G., Truong, S. K., Do, H. H., and Vincent, A. C. J. (2006). The catch and trade of seahorses in Vietnam. Biodiversity and Conservation 15, 2497–2513.
| The catch and trade of seahorses in Vietnam.Crossref | GoogleScholarGoogle Scholar |
Gokulakannan, K. (2002). Systematics of seahorses and biology of yellow seahorse Hippocampus kuda (Bleeker, 1852) from Palk Bay region, south-east coast of India. Ph.D. Thesis, Annamalai University, India.
Government of Tamil Nadu (1983). Tamil Nadu Marine Fishing Regulation Rules, 1983. Available at http://extwprlegs1.fao.org/docs/pdf/ind188851.pdf [Verified 25 August 2021]
Hammer, Ø., Harper, D. A., and Ryan, P. D. (2001). PAST: paleontological statistics software package for education and data analysis. Palaeontologia Electronica 4, 9.
Ignatius, B., and Jagadis, I. (2003). Growth and reproduction of tropical seahorse Hippocampus kuda in captivity. Indian Journal of Fisheries 50, 369–372.
Jiaxin, C. (1990). Brief introduction to mariculture of five selected species in China (Section 1: Seahorse culture). Working Paper. FAO/UNDP Regional Sea farming Development and Demonstration Project, Bangkok, Thailand.
Linehan, J. E., Gregory, R. S., and Schneider, D. C. (2001). Predation risk of age-0 cod (Gadus) relative to depth and substrate in coastal waters. Journal of Experimental Marine Biology and Ecology 263, 25–44.
| Predation risk of age-0 cod (Gadus) relative to depth and substrate in coastal waters.Crossref | GoogleScholarGoogle Scholar |
Lipton, A. P., and Thangaraj, M. (2002). Present status of seahorses fishing along the Palk Bay coast of Tamil Nadu. Marine Fisheries Information Service Technical and Extension Series 174, 5–8.
Lourie, S. A., Vincent, A. C., and Hall, H. J. (1999). ‘Seahorses: An Identification Guide to the World’s Species and their Conservation’, (Project Seahorse: London, UK.)
Lourie, S. A., Pollom, R. A., and Foster, S. J. (2016). A global revision of the seahorses Hippocampus Rafinesque 1810 (Actinopterygii: Syngnathiformes): taxonomy and biogeography with recommendations for further research. Zootaxa 4146, 1–66.
| A global revision of the seahorses Hippocampus Rafinesque 1810 (Actinopterygii: Syngnathiformes): taxonomy and biogeography with recommendations for further research.Crossref | GoogleScholarGoogle Scholar | 27515600PubMed |
Moreau, J., and Cuende, F. X. (1991). On improving the resolution of the recruitment patterns of fishes. Fishbyte 9, 45–46.
Morgan, S. K., and Vincent, A. C. (2013). Life-history reference points for management of an exploited tropical seahorse. Marine and Freshwater Research 64, 185–200.
| Life-history reference points for management of an exploited tropical seahorse.Crossref | GoogleScholarGoogle Scholar |
Murugan, A., Dhanya, S., Sreepada, R. A., Rajagopal, S., and Balasubramanian, T. (2009). Breeding and mass-scale rearing of three spotted seahorse, Hippocampus trimaculatus Leach under captive conditions. Aquaculture 290, 87–96.
| Breeding and mass-scale rearing of three spotted seahorse, Hippocampus trimaculatus Leach under captive conditions.Crossref | GoogleScholarGoogle Scholar |
Murugan, A., Dhanya, S., Sarcar, A. B., Naganathan, V., Rajagopal, S., and Balasubramanian, T. (2011). Fishery biology, demography of three spotted seahorse, Hippocampus trimaculatus inhabiting Gulf of Mannar region, south-east coast of India. Indian Journal of Geo-Marine Sciences 40, 408–411.
Pauly, D. (1979). Gill size and temperature as governing factors in fish growth: a generalization of von Bertalanffy’s growth formula. Ph.D. Thesis, Christian-Albrechts-Universität Kiel, Kiel, Germany.
Pauly, D. (1980). On the interrelationships between natural mortality, growth parameters, and mean environmental temperature in 175 fish stocks. ICES Journal of Marine Science 39, 175–192.
| On the interrelationships between natural mortality, growth parameters, and mean environmental temperature in 175 fish stocks.Crossref | GoogleScholarGoogle Scholar |
Pauly, D. (1983). Length-converted catch curves: a powerful tool for fisheries research in the tropics (part 1). Fishbyte 1, 9–13.
Pauly, D. (1984). Fish population dynamics in tropical waters: a manual for use with programmable calculators. ICLARM Studies and Reviews 8, 1–325.
Pauly, D., and Munro, J. L. (1984). Once more on the comparison of growth in fish and invertebrate. ICLARM Fishbyte 2, 1–21.
Pawar, H. B. (2014). Development and Standardization of Culture Techniques for Conservation of Yellow Seahorse, Hippocampus kuda (Bleeker, 1852). Ph.D. Thesis, Goa University, Goa, India.
Pianka, E. R. (1970). On r and K selection. American Naturalist 104, 592–597.
| On r and K selection.Crossref | GoogleScholarGoogle Scholar |
Richu, A., Dahanukar, N., Ali, A., Ranjeet, K., and Raghavan, R. (2018). Population dynamics of a poorly known serranid, the duskytail grouper Epinephelus bleekeri in the Arabian Sea. Journal of Fish Biology 93, 741–744.
| Population dynamics of a poorly known serranid, the duskytail grouper Epinephelus bleekeri in the Arabian Sea.Crossref | GoogleScholarGoogle Scholar | 30051476PubMed |
Salin, K. R. (2003). Reproductive Biology and Larval Rearing of Hippocampus kuda, and the taxonomy of seahorses (Hippocampus spp.) along the southern coast of India. Ph.D. Thesis, Central Institute of Fisheries Education, Mumbai, India.
Salin, K. R., Yohannan, T. M., and Mohanakumaran Nair, C. (2005). Fisheries and trade of seahorses, Hippocampus spp., in southern India. Fisheries Management and Ecology 12, 269–273.
| Fisheries and trade of seahorses, Hippocampus spp., in southern India.Crossref | GoogleScholarGoogle Scholar |
Scales, H. (2010). Advances in the ecology, biogeography and conservation of seahorses (genus Hippocampus). Progress in Physical Geography 34, 443–458.
| Advances in the ecology, biogeography and conservation of seahorses (genus Hippocampus).Crossref | GoogleScholarGoogle Scholar |
Sheng, J., Lin, Q., Chen, Q., Gao, Y., Shen, L., and Lu, J. (2006). Effects of food, temperature and light intensity on the feeding behaviour of three-spot juvenile seahorses, Hippocampus trimaculatus Leach. Aquaculture 256, 596–607.
| Effects of food, temperature and light intensity on the feeding behaviour of three-spot juvenile seahorses, Hippocampus trimaculatus Leach.Crossref | GoogleScholarGoogle Scholar |
Shokri, M. R., Gladstone, W., and Jelbart, J. (2009). The effectiveness of seahorses and pipefish (Pisces: Syngnathidae) as a flagship group to evaluate the conservation value of estuarine seagrass beds. Aquatic Conservation 19, 588–595.
| The effectiveness of seahorses and pipefish (Pisces: Syngnathidae) as a flagship group to evaluate the conservation value of estuarine seagrass beds.Crossref | GoogleScholarGoogle Scholar |
Simberloff, D. (1998). Flagships, umbrellas, and keystones: is single-species management passé in the landscape era? Biological Conservation 83, 247–257.
| Flagships, umbrellas, and keystones: is single-species management passé in the landscape era?Crossref | GoogleScholarGoogle Scholar |
Taylor, C. C. (1958). Cod growth and temperature. ICES Journal of Marine Science 23, 366–370.
| Cod growth and temperature.Crossref | GoogleScholarGoogle Scholar |
Thangaraj, M., Lipton, A. P., and Victor, A. C. C. (2006). Onset of sexual maturity in captive reared endangered Indian seahorse, Hippocampus kuda. Current Science 91, 1714–1716.
Vaidyanathan, T., Zhang, X., Balakrishnan, R., and Vincent, A. (2021). Catch and trade bans for seahorses can be negated by non‐selective fisheries. Aquatic Conservation 31, 43–59.
| Catch and trade bans for seahorses can be negated by non‐selective fisheries.Crossref | GoogleScholarGoogle Scholar |
Vaitheeswaran, T., and Venkataramani, V. K. (2012). Length weight relationship of Hippocampus kuda (Bleeker, 1852) (Family: Syngnathidae), off Thoothukudi waters, south-east coast of India. Tamilnadu Journal of Veterinary and Animal Sciences 8, 119–125.
Vaitheeswaran, T., Jayakumar, N., and Venkataramani, V. K. (2012). Age and growth of seahorse Hippocampus kuda (Bleeker, 1852) (Family: Syngnathidae) from Thoothukudi, south-east coast of India. Tamilnadu Journal of Veterinary and Animal Sciences 8, 203–208.
Vincent, A. C. J. (1996). ‘The International Trade in Seahorses’, (TRAFFIC International: Cambridge, UK.)
Vincent, A. C., Foster, S. J., and Koldewey, H. J. (2011). Conservation and management of seahorses and other Syngnathidae. Journal of Fish Biology 78, 1681–1724.
| Conservation and management of seahorses and other Syngnathidae.Crossref | GoogleScholarGoogle Scholar | 21651523PubMed |
Vincent, A. C., Sadovy de Mitcheson, Y. J., Fowler, S. L., and Lieberman, S. (2014). The role of CITES in the conservation of marine fishes subject to international trade. Fish and Fisheries 15, 563–592.
| The role of CITES in the conservation of marine fishes subject to international trade.Crossref | GoogleScholarGoogle Scholar |
von Bertalanffy, L. (1938). A quantitative theory of organic growth (Inquiries on growth laws. II). Human Biology 10, 181–213.
Wiswedel, S. (2015). Three-spot Seahorse Hippocampus trimaculatus. In ‘The IUCN Red List of Threatened Species 2015’. e.T10087A17252219. (International Union for Conservation of Nature and Natural Resources.) Available at https://www.iucnredlist.org/species/10087/17252219 [Verified 27 April 2021].
Zar, J. H. (1999). ‘Biostatistical Analysis’, 4th edn. (Prentice Hall: Upper Saddle River, NJ, USA.)
