The importance of the surf zone as a nursery ground for larval and juvenile fishes has been widely recognized, however the zone has yet to be studied in Mauritius. Recently, the coastal area of the island has been increasingly affected by human activities, especially by tourism. We collected fish samples with a hand pulled seine net during the period of August 2001 to March 2003 to clarify the fish fauna and the dynamics of fishes in the surf zone. Two sampling sites adjacent to river mouth areas and one sampling site adjacent to a mangrove area were selected for comparison of fish fauna in relation to environmental conditions. A total of 9,429 fish larvae and juveniles, representing at least 112 species from 48 families were collected. The abundant species were hardyhead silverside, Atherinomorus lacunosus, bluespot mullet, Valamugil seheli, and Ambassis spp., each contributing 16.2, 12.4, and 11.8% of the total number of individuals, respectively. Estuarine species dominated in the surf zone adjacent to the river mouth areas. Species composition and diversity changed seasonally. The number of fish increased during the rainy season. Species diversity increased at the turn of the seasons from the dry season to the rainy season. We conclude that species composition in each site was affected by environmental factors, such as the scale of the flux from the rivers, which is related to the precipitation. The results indicated that freshwater from the river is a trigger to aggregate larvae and juveniles in the surf zone.

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Artificial reefs (ARs) are one of the most popular means of supporting marine ecosystem conservation and coastal fisheries, particularly in developing countries. However, ARs generate complex socio-bio-economic interactions that require careful evaluation. This is particularly the case for ARs outside no-take zones, where fish might be subject to enhanced exploitation due to easier catchability. Here, we conducted an interdisciplinary study on how ARs impact fish and fishing yields, combining mathematical and sociological approaches. Both approaches converge to confirm that fishery yields decline when ARs are exploited as if they were open access areas. This situation typically occurs in areas with weak governance and/or high levels of illegal fishing activity, both of which are common in many developing countries. To avoid these adverse effects and their associated ecological consequences, we recommend prioritizing the onset of a long-term surveillance system against illegal fishing activities, and adapting design and location of the ARs based on both and local and academic knowledge, before the deployment of ARs.

Three species of the family Scombridae, viz. Auxis thazard, Katsuwonus pelamis, and Thunnus thynnus were studied for their karyotypes and cellular DNA contents. The first species is unknown as to its karyotypes or its cellular DNA content , which are described below. The diploid number of these three species is invariably 48 , and composed of acrocentric chromosome in Auxis thazard and Katsuwonus pelamis , but in Thunnus thynnu s the karyotype is composed of one pair of metacentric , two pairs of subtelocentric, and 21 pairs of acrocentric chromosomes. The DNA contents are 1.8pg/cell in Auxis thazard and 2.00pg/cell in Katsuwonus pelamis, these values are being included in the range of typical ones as members of the teleost group. Relative chromosome size ranges from about 1.2%to3.3%, showing almost unimodal composition in size. The karyotypes of these three species of the family Scombridae are characterized by a smaller variability in size of chromosomes.