Fish ecology and biology


sey-cous-jude jan sutures-ms09Our research on the biological and ecological aspects of reef fishes is designed to understand the most effective ways of managing them in the context of species vulnerability, government and community based approaches to management, existing fishing methods and community dependence and climate change. more information can be downloaded from here.

 

 

 

 

Vulnerable Grouper
Vamiz5&6 sep11_29 Plect punctatus smlAs a member of the IUCN Species Specialist Group on Groupers and Wrasses Melita has done several desk based assessments for Red Listing and participated in the SSG workshops. She has contributed data and information from the WIO to global assessments of widely distributed Indo-Pacific species of groupers as well as Indian Ocean endemics, including information on the rare Somali grouper. This produced a global assessment of groupers by the SSG members (Sadovy et al. 2012 fishing groupers to extinction). Melita was also invited to give a keynote address on: “Grouper fisheries and their management in the Western Indian Ocean and Red Sea” at the Regional Symposium on the Biology, Assessment and Management of Groupers, in Abu Dhabi in 2008.
Spawning aggregations
crrt mtr-cou-ms09-tying to blockA wide range of reef fishes aggregate in large numbers to spawn, including many species from highly valued food fish families. Reef fish species forming spawning aggregations are often highly mobile, with migrations to spawning sites ranging from a few to hundreds of kilometres. Targeted fishing of aggregations in the early stages of exploitation can generate very high catch rates and revenues, but it is generally believed that such levels of exploitation are unsustainable.

This research programme, which spanned Kenya, Seychelles and Zanzibar, was initiated because it was inevitable that aggregative spawners are subject to increasing fishing pressure in the region while very little was known regarding their stock status and the health of their spawning aggregations. The overall goal of the research was to address critical information gaps and develop robust scientific approaches for the management and conservation of commercially important species that aggregate to spawn in the WIO. The research results are detailed in a book published in 2013 WIOMSA-CORDIO spawning book full. The research demonstrated the feasibility of using basic information from spawning aggregation-based fisheries to systematically evaluate management needs in data-poor contexts. This was achieved through a conceptual approach  that involved estimation of key aggregation and fishery parameters and the application of those parameters in a vulnerability assessment and a no-take reserve (NTR) model for spawning aggregations. Conservation initiatives would benefit from explicitly incorporating assessment and management of spawning aggregation-based fisheries. Moreover, S. sutor- tagging Msambweniconservation initiatives would benefit from avoiding the over-generalisation, lack of quantitative evaluation and ethical and validity issues that have sometimes emerged in other regions. Clearly, the conservation imperative is influenced by the fact that most research to date has focused on the more vulnerable aggregative spawners such as groupers. However, recognition that some aggregative spawners are relatively resilient to fishing is needed and the socio-economic aspects of the system must be understood (Robinson et al 2011). Upon verification of an aggregation-based fishery and when status information is lacking, it is necessary to consider taxa-specific vulnerability to fishing and the potential costs and benefits of both conservation and fisheries management approaches. The data-poor tools used in the studies described here can provide rapid information in such contexts. In Kenya this research has led to a community closure for one of the rabbitfish spawning aggregations.  (link to Protecting spawning aggregation story in LMMAs in Kenya folder).

Shark
Underwater surveys on reefs in Tanzania, Comoros, Madagascar and Mozambique to assess population densities of large reef associated fishes recorded no sharks except for one site in Cabo Delgado, northern Mozambique; in contrast sharks in Chagos were observed at most reefs. Tiger SharkThese results combined with concerns on the status of sharks worldwide (www.iucnssg.org/) led us to raise funds in 2014 for pilot research on sharks designed to raise awareness and improve management. With colleagues from Windsor University and the Zoological Society of London we are using satellite tags on tiger sharks to assess their movements and to raise awareness of shark conservation regionally. http://www.zsl.org/conservation/habitats/marine-and-freshwater/indian-ocean-tigers Our current work is compiling shark records from artisanal fisheries in Kenya and Mozambique.