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Correia M.,University of Algarve | Caldwell I.R.,Hawaii Institute of Marine Biology | Koldewey H.J.,Project Seahorse | Andrade J.P.,University of Algarve | Palma J.,University of Algarve
Journal of Fish Biology | Year: 2015

Comparisons of three sets of surveys in the Ria Formosa Lagoon, Portugal, over a 13 year period (2001-2002, 2008-2009 and 2010-2013) revealed significant population fluctuations in at least one of the two seahorse (Hippocampinae) species living there, and that those fluctuations were potentially associated with habitat changes in the lagoon. After a significant decline between the first two survey periods (2001-2002 v. 2008-2009), long-snouted seahorse Hippocampus guttulatus populations increased significantly between 2008-2009 surveys and new 2010-2013 surveys. There were no significant differences in H. guttulatus populations between the 2001-2002 and 2010-2013 surveys. In contrast, there were no significant differences in short-snouted seahorse Hippocampus hippocampus densities among the 16 sites surveyed throughout the three sampling periods, although the ability to detect any change was hampered by the low densities of this species in all time periods. Fluctuations in H. guttulatus densities were positively correlated with the percentage of holdfast coverage, but with none of the other environmental variables tested. These results highlight the importance of holdfast availability in maintaining stable seahorse populations. While population fluctuations are certainly more promising than a consistent downward decline, such extreme fluctuations observed for seahorses in the Ria Formosa Lagoon could still leave these two species vulnerable to any additional stressors, particularly during low density periods. © 2015 The Fisheries Society of the British Isles. Source

Correia M.,University of Algarve | Palma J.,University of Algarve | Koldewey H.,Project Seahorse | Andrade J.P.,University of Algarve
Journal of Fish Biology | Year: 2014

In this study, the spot pattern in Hippocampus guttulatus was analysed using a computer programme algorithm that allowed individual comparison. This methodology was first tested in a controlled environment using 51 adult and 55 juvenile H. guttulatus. Positive matches were obtained in 86·3 and 83·6% of the adults and juveniles, respectively. In a second experiment, monthly surveys were carried out in five selected locations in the Ria Formosa Lagoon, south Portugal, over the course of a year and a total of 980 photographs were analysed. Photographed H. guttulatus were re-sighted one to nine times during the course of the survey period with an overall re-sight record of over 30%. Photo-identification was therefore shown to be a useful tool for non-invasive mark-recapture studies that can be successfully used to survey the population abundance of H. guttulatus aged 6months or older in consecutive years. This could be of great value when considering the assessment of H. guttulatus populations and understanding changes over time. © 2014 The Fisheries Society of the British Isles. Source

Correia M.,University of Algarve | Koldewey H.,Project Seahorse | Andrade J.P.,University of Algarve | Palma J.,University of Algarve
Regional Studies in Marine Science | Year: 2015

Two different Underwater Visual Census (UVC1 and UVC2) were performed at three sites in the Ria Formosa, using 30 meter transect belts, and compared for differences in seahorse density and holdfast availability. Each UVC differed in transect placement and total survey area coverage. The observed Hippocampus guttulatus density was significantly higher (P<0.05) using UVC2 for Site 1 and Site 2, but not in Site 3. No statistically significant differences were found in holdfast availability (P>0.05) between the two UVC methods. We conclude that the UVC2 method is more effective in quantifying abundance of seahorses compared with UVC1, particularly in low population density scenarios. This method can also be used in assessing other seahorse species' populations, in similar habitats. © 2015 Elsevier B.V. Source

Woodall L.C.,Royal Holloway, University of London | Koldewey H.J.,Project Seahorse | Shaw P.W.,Royal Holloway, University of London
Journal of Fish Biology | Year: 2011

This first genetic study of Hippocampus hippocampus covers the species' entire geographic range and employs two mtDNA markers (control region and cytochrome b) to establish patterns of population structuring. A total of 255 specimens from 21 locations were used to obtain 89 concatenated haplotypes. The common haplotype was present in all but one population, however, most haplotypes were unique. The haplotype network had a star-like construction, suggesting expansion from a bottleneck event. FST and AMOVA revealed population subdivision into three geographic regions (English Channel + Bay of Biscay, Mediterranean Sea + Atlantic Ocean Iberian coast + Macaronesian Islands, and West Africa) with barriers to gene flow indentified at Cape Finisterre and the Cape Verde frontal zone. Neutrality tests and nested clade analysis suggest a complex demographic history, with both historic events and contemporary processes shaping patterns of genetic differentiation. The genetic population subdivision detected in this study indicates that H. hippocampus should be managed as three separate units. This is especially pertinent as H. hippocampus populations within the West African region are the only ones known to be specifically targeted for exploitation. © 2011 The Authors. Journal of Fish Biology © 2011 The Fisheries Society of the British Isles. Source

Koldewey H.J.,Project Seahorse | Martin-Smith K.M.,University of Tasmania
Aquaculture | Year: 2010

Seahorses (Hippocampus spp.) are flagship species for many issues in marine conservation including overexploitation, incidental bycatch and habitat loss. Aquaculture has been proposed as one solution to address unsustainable trade for traditional medicine, aquarium fishes and curios. Here we review historical and current information on global seahorse aquaculture including characteristics of aquaculture operations, species in culture, contribution to international trade and technical issues associated with raising seahorses in captivity. We found that prior to the 1990s, seahorse aquaculture was plagued by problems with disease and feeding. In the late 1990s and early 2000s there was considerable expansion in the number and size of aquaculture operations and the number of species in culture. This was reflected in an increasing contribution of captive-bred seahorses to the aquarium trade but not in the larger traditional medicine market. Currently, the majority of seahorse aquaculture involves small-scale operations in developed countries, employing relatively few personnel and selling live animals for the home aquarium market. Although, there are still considerable technical problems with diseases and with breeding and raising some species, others are performing successfully in aquaculture. There are currently at least 13 species in commercial culture or under research for their culture potential. However, economic viability remains a concern to many current aquaculture operations including price competition with wild-caught animals. Large-scale aquaculture to supply the traditional medicine market or as a livelihood venture has not yet been demonstrated to be commercially viable, although it is being actively researched. © 2009 Elsevier B.V. All rights reserved. Source

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