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Major decline in demersal fish stocks, says ERWDA survey

DUBAI - Coastline modifications in the UAE, including activities as dredging

Land reclamation and channelling of the sea-bed, have paralleled major declines of demersal fish stocks.

This is part of the findings of the fish resource assessment survey project conducted from February 2, 2002, to January 23, 2003 on the demersal and small pelagic resources of the UAE by the Environmental Research and Wildlife Development Agency (ERWDA).

The project has provided the first fisheries independent data of the UAE's demersal and small pelagic resources in over 25 years and the first-ever comprehensive survey of these resources.

The report of the survey said: "The fact that both commercial and non- commercial stocks have been affected strongly suggests that the major cause of these declines is due to environmental changes and habitat degradation."

It said that a paradigm shift in the management of fish resources from fisheries-based approaches to more integrated ecosystem approaches that are also cross sector is required.

The report said that the fish stocks, including demersal fish resources, appear to be part of the large stock inhabiting the Arabian Gulf and the Gulf of Oman. Consequently, these stocks cannot be managed in isolation by each emirate and meaningful cooperation and coordination, both at the national and regional level is required, the report emphasised.

"There is an urgent need for more studies (tagging and mtDNA) to determine the movement and stock structure of the mobile component of the demersal fish stocks," it said.

The survey found that the Arabian Gulf waters, specially the waters off the emirate of Abu Dhabi, are a significant spawning area for many demersal fish species, both mobile and resident. There appears to have been major decline in the abundance of demersal fish resources, both commercial and non commercial since 1978 and these declines cannot be explained in terms of overfishing alone, the report added.

It said that almost all commercial major species were being exploited to their maximum potentials. "Although the abundance of the small pelagic resources has not changed, the school sizes exhibited by these species are relatively small making any attempts at commercial exploitation of these resources difficult," the report said.

The survey was carried out by a consortium led by Bruce Shellard and Associates of New Zealand. The overall objective of the survey was to conduct an assessment of fish and marine resources of the UAE waters by acoustic survey supplemented by fishing operations to make available information on the abundance and distribution of fish and marine resources in the area and to estimate their potential yield.

Using research vessel Flinders, every effort was made to ensure that the survey covered UAE's exclusive economic zone as much as possible.

Overall, the survey involved 12 cruises covering 200 sea days in which 250 trawl stations and over 20,000km of acoustic transects were made. Also environmental and oceanographic data were collected from fixed oceanographic stations. Further oceanographic data were collected from satellite imagery.

UAE waters exhibited characteristics of two distinct water bodies. While the East Coast displayed conditions that were much more oceanic with small seasonal fluctuations in temperature and salinity, the Arabian Gulf waters had greater hydrographic fluctuations as would be expected of a shallow and confined water basin. This situation was particularly more pronounced in the waters off the emirate of Abu Dhabi.

There is a close correlation between the abundance and distribution of fish resources on one hand, and oceanographic environmental conditions on the other hand, the survey found.

The results of the survey not only provide comprehensive information on relative abundances of species but also give detailed information on yields, catch rates and distribution of demersal species.