The date today is 09-02-09

1950 to Present Day Pt3

As the scallop fishery expanded outside of the Firth of Clyde and new fishing grounds were discovered in the mid-1970s, it was found that the size of scallops and the number of rings on their shells were much greater than those in the Clyde[i], showing the effects of exploitation on the age structure of a population. After 40 years of fishing in the Clyde, scallops were simply not reaching their former sizes and ages.

Concerns were raised in 1975 by fishers about the conservation of scallops and queens, as 3 and 4 ring scallops now made up more than 50% of the catch, but results of investigations failed to show severe overfishing[ii].

Landings of scallops in the Firth of Clyde between 1987 and 2006. Source: SFPA

The Nephrops fishery

Total demersal catch increases in the 1960s and 1970s were almost entirely due to a rise in trawling for Nephrops67, which came about as prices for scampi increased and as fishers diversified. Nephrops are now caught by trawlers and to a lesser extent, creels, which tend to catch high quality Nephrops that are then transported live to the continent. Nephrops is now the most valuable fishery in the Clyde area, with around 120 vessels dedicated to this fishery and 90% of landings made by resident Clyde trawlers[iii].

The majority of Clyde fishers are now reliant on this single species, with the stock currently thought to be being fished sustainably[iv]. A limited number of days at sea and mesh size restrictions are in place to prevent over-exploitation[v], but this fails to protect habitats and non-target species. Discard ratios are extremely high in the Clyde Nephrops fishery, with 9kg of bycatch produced for every 1kg of Nephrops caught84. 25,000 tonnes of discards are generated every year in the Firth of Clyde from Nephrops trawling alone[vi], many of which die when returned to the sea[vii]. Discards also provide food for scavenging seabirds and benthic animals, probably subsidising scavenging populations and changing the composition of communities85.

Landings of Nephrops in the Firth of Clyde. An increase in the 1980s and 90s occurred, with landings fluctuating but remaining relatively stable since. Landings values are slightly different from earlier statistics in the 1970s and 1980s because these results incorporate a different area of the Clyde, being taken from vessels landing at Clyde ports which may have worked outside of the area. Source: SFPA.

 

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[i] Department of Agriculture and Fisheries for Scotland (1975). Fisheries of Scotland report for 1974. Edinburgh, UK.

[ii] Department of Agriculture and Fisheries for Scotland (1976). Fisheries of Scotland report for 1975. Edinburgh, UK.

[iii] ICES WGNSDS Report (2006). Annex 5: Quality Handbook: WGNSDS - Clyde Nephrops (FU13).

[iv] http://www.gla.ac.uk/centres/marinestation/CFDP/index.htm

[v] Bergmann, M., Wieczorek, S.K., Moore, P.G. and Atkinson, R.J.A (2002). Discard composition of the Nephrops fishery in the Clyde Sea area, Scotland. Fisheries Research 57: 169-183.

[vi] Bergmann, M., Wieczorek, S.K., Moore, P.G. and Atkinson, R.J.A (2002). Utilisation of invertebrates discarded from the Nephrops fishery by variously selective benthic scavengers in the west of Scotland. Marine Ecology Progress Series 233: 185-198.

[vii] Bergmann, M. and Moore, P.G (2001). Mortality of Asterias rubens and Ophiura

ophiura discarded in the Nephrops fishery of the Clyde Sea area, Scotland. ICES Journal of Marine Science 58: 531-542.

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