What do we know about fish stocks in the Southern Scotia region? A review and prospects for future research

Work on finfish in the southern Scotia Arc was restricted to taxonomy until the end of the 1960’s. Commercial exploitation, primarily on mackerel ice fish, Champsocephalus gunnari, and marbled notothenia, Notothenia rossii, started around the South Orkney Islands (60 – 62° / 43 – 47° W) in 1977/78 and close to Elephant Island and the lower South Shetland Islands (60 – 62° S / 54 – 62° W) in 1978/79. The fishery was lucrative for a few seasons only, and was closed in 1989/90.
Stocks of finfish suffered substantial declines during the period the fishery was open. Most fish stocks, with the exception of mackerel ice fish and marbled notothenia, had recovered from exploitation by the end of the 1980’s/beginning of the 1990’s. Since the early 1990’s, most species appeared to have changed little in abundance, and followed primarily fluctuations in year-class strength and the environment. However, stocks of mackerel ice fish, which had formed the backbone of the fishery remained only small proportions of their initial sizes.
Most information on biological parameters of finfish stocks stemmed from Soviet, Polish, German and recent American research in the area. Two elements of the fish fauna overlapped in the southern Scotia Arc region: peri-Antarctic or Lesser Antarctic species and high-Antarctic species. Peri-Antarctic species prevailed in terms of weight and numbers. High-Antarctic species occurred regularly albeit in small numbers, and played a negligible role in terms of biomass. Among the three subareas, the fish fauna around the South Orkney Islands was the least known. Basic biological parameters of fish species, such as vertical and horizontal distribution, reproduction, age and growth, food preferences and feeding (except in the South Orkney Islands) were comparatively well known although some gaps in our knowledge still existed. Age and growth of most species were poorly understood. Major deficiencies were apparent in the understanding of the early life history of many species. Future work should focus on filling in the gaps in the biology of species, intensifying synecological work and better describing the relationships of fish species with each other, predator-prey relationships both with other fish species and seals and birds, the food consumption of fish species, and their interactions with the environment.