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The rapid catch of marine megafauna (marine mammals, sea turtles and elasmobranchs) poses a threat to these vulnerable species.The purpose of this study is to assess bycatch and use of vulnerable megafauna (marine mammals, sea turtles and elasmobranchs) in the SWIO artisanal fisheries using interview surveys. This study focuses on areas where bycatch of vulnerable megafauna has been previously identified, suspected or least known as for the east coast of Africa (Mozambique). This study also provides recommendations for future research, management and mitigation of vulnerable megafauna bycatch in artisanal fisheries of the SWIO region Results collected in this study are consistent with previous local studies, undertaken in the southwest Indian Ocean, both in term of species involved and bycatch incidence.
The hydroacoustic survey covered the shelf and slope to about 2500 m bottom depth. Continuous acoustic recording and analysis was carried throughout the survey. Pelagic trawling was carried out for pelagic species identification, mainly during dark hours, either as random blind trawl hauls close to the surface with pelagic trawl equipped with large floats, or on registrations. In addition blind surface hauls were made at intervals and at the start and end of each environmental transect to determine the distribution and species composition of juvenile fish. The highest acoustic densities where found over the shelf and shelf break while further out the recordings were lower and the catches more dominated by plankton and mesopelagic fish towards deeper waters. The dispersed fish distribution and high abundance of plankton made acoustic detection and separation very difficult, and thresholding according to the Cotel methods were used. The acoustic estimates for the pelagic species groups PEL 1 (Clupeidae) and PEL 2 (Carangidae, Sphyraenidae, Trichiuridae and Scombridae) shown a biomass of 6.1× and 3.5× higher than the estimate presented in the 2007 Ecosystem Survey report for the whole Mozambique coast. The differences between the 2007 and present survey acoustic estimates should not be taken as indications of large increases in species abundance. During the present survey new methods for analysing and interpreting the acoustic data were used and these methodological differences are probably the major cause in the differences in abundance between 2007 and 2009. Pelagic species were observed both acoustically and in trawl catches along the whole survey track. The PEL 1 group was observed from 10° -13° 30’S, then from 14° S to the end of the survey. In 2007 no PEL 1 was observed in this region. The main distribution was over the shelf, but PEL1 were also observed over deeper (>1000m) waters. The PEL 2 group (Carangidae, Sphyraenidae, Trichiuridae and Scombridae) were found from 11° 30’S to the southern end of the survey. The main distribution area was over the shelf and shelf break, but like the PEL 1 group the distribution extended into deeper (>1000m) waters. Compared to the 2007 survey the distribution was wider and extended further to the north. Zooplankton was sampled at 42 stations using the multinet. The multinet was deployed after measuring the fluorescence profile using the fluorometer mounted on the CTD rosette. Nets were deployed at different depths above and below the depth of highest fluorescence: two above f-max, one through f-max, two below f-max. Samples for the multinet have been preserved in formalin solution but not analyzed in any way. Therefore, no results from the zooplankton investigations can be reported in this preliminary survey report. During the survey a total of 213 species were identified. The fish species caught are grouped according to functional groups. Pelagic trawl catches of fish were grouped according to fish depth of the trawl. In the surface layer the ‘Other’ and ‘Scombrids’ groups dominated due to one or two very large catches. Down to 20 meters the ‘Other’ group still dominated but here hairtails as the second most important. At 20-100 meters Clupeids were the dominant group with one catch 10× as large as the second largest. Deeper than 100 meters the mesopelagic fish dominated, although the catch rates were less than closer to the surface. Dedicated observations of marine mammals were carried out on 19 August along the coast while steaming towards Pemba. The course was set close to shore to cover bays where whales and birds had been observed during surveying southwards. A total of 31 birds and 29 humpback whales were observed from 06:10 to 17:38. A large school of fish was seen feeding actively at the surface next to a mangrove forest. Feeding continued for over 15 minutes and the fish were repeatedly jumping out of the water.
The East African coastal region was divided into three areas: Northern, Central and Southern regions. The original intention was to make regular bi-monthly longlining cruises, alternating northern and southern areas with certain central areas sampled on each cruise but constant mechanical failures in MANIHINE before or during cruises made it impossible to follow the laid down programme; hence the erratic nature of the fishing and sampling heavily biased towards the North East monsoon. This report gives an outline of the major features of the water masses.
The physio-chemical environment of the fishing area is rapidly described here; this area is limited by the Malagasy North West coast, the Comores Islands, the Aldabra and Providence Islands. This area is favorable to great tuna concentrations and the following report gives tuna and live-bait fishing results, for Madagascar.
This is a report for cruise 2 of the R/V Anton Bruun that includes station lists for plankton collections, bathythermograph positions, and reduced oceanographic, chemical, and biological data. In addition to the basic hydrographic and biological programs and the researches of individual scientists, a special program of long-line fishing was carried out in a cooperative with the U.S. Bureau of Commercial Fisheries.
Cruise 3 of the R/V ANTON BRUUN, originating from Bombay and terminating at Port Louis, Mauritius in 1963, was the first Cruise on which a special effort was made to sample the meso- and bathypelagic fauna on the western Indian Ocean. This report presents the reduced oceanographic, chemical and biological data, station lists of plankton, midwater trawl, miscellaneous biological collections and bathythermograph positions for Cruise 3.
In 1981 a Joint Fisheries Research Project of the Republic of Seychelles and the Federal Republic of Germany was carried out in the area of Seychelles. Two chartered trawlers performed 108 valid hauls with one-boat trawl on the Mahe Plateau. Density, total biomass and potential yield of demersal fish was estimated. This report covers the results on bottom fish of the Mahe plateau.
The Southern Indian Ocean seamounts expedition achieved many of its sampling objectives. The data gathered are likely to form a significant contribution to knowledge in the following areas: • Hydrographic structure of the Sub-Tropical Convergence zone • Patterns of chlorophyll concentration, nutrient chemistry and phytoplankton diversity from the oligotrophic Sub-Tropical Anticyclonic Gyre system through the Sub-Tropical Front to Sub-Antarctic waters • Small scale current topography interactions around seamounts with differing summit heights, including evidence of tidally driven concentration and / or mixing of water and phytoplankton and influence on the distribution of zooplankton • Trapping of multiple deep-scattering layers of zooplankton and predation by resident seamount predators • Evidence supporting proposed biogeographic zones within the southern Indian Ocean • Evidence of the significance of both water masses and the presence of elevated topography on seabird distributions • Connectivity of populations of pelagic organisms across the South West Indian Ocean Ridge The extremely large number of specimens gathered during this expedition means that a large post-cruise effort will be required in order to extract the maximum information from the cruise. These data will be most significant when combined across the disciplines of oceanography, biogeochemistry, botany and zoology represented on the cruise by the scientists.
The primary purpose of the Galathea Expedition was to explore the ocean trenches in order to find out find out whether life occurred under the extreme conditions prevailing there and if so, to what extent. The second objective was to seek more information, by making greater use of large-scale dredging implements that had been done in the past, as to whether, and to what extent, there are large and active animals in the abyss. The study was also focused on the bottom fauna; to determine the amount of living animals per square metre of sea-bed by a method first employed in Danish waters. The scientific objectives of the expedition were to carry out biological and oceanographical research and make collections, principally in abyssal waters. It also endeavored to spread a knowledge of Danish culture and economic life by means of lectures, films etc.
Cruise 5 of the R/V ANTON BRUUN originated from Bombay on January 26 and terminated at Bombay on May 4, 1963. A special program of longline fishing was conducted to study the distribution and abundance of pelagic fishes in the Western Indian Ocean in the period of northeast monsoon. This report presents the station lists, bathythermograph positions and reduced oceanographic, chemical and biological data for Cruise 5. It includes a summary of the longline catch by stations.