CCAMLR

The role of fish in the Antarctic food web in inshore and offshore waters is analysed taking as an example the coastal marine communities of the southern Scotia Arc (South Orkney Islands and South Shetland Islands) and the west Antarctic Peninsula. Inshore, the ecological role of demersal fish is more important than that of krill. There, demersal fish are major consumers of benthos and also feed on zooplankton (mainly krill in summer), and are links between lower and upper levels of the food web; they are common prey of other fish, birds and seals. Offshore, demersal fish depend less on benthos and feed more on zooplankton (mainly krill) and nekton, and are less accessible as prey of birds and seals. There, pelagic fish (especially lanternfish) are more abundant than inshore and play an important role in the energy flow from macrozooplankton to higher trophic levels (seabirds and seals). Through the higher fish predators, energy is transferred to land in the form of fish remains, pellets (birds), regurgitations and faeces (birds and seals). But in the wide context of the Antarctic marine ecosystem, krill (E. superba) plays the central role in the food web because it is the main food source in terms of biomass for most of the high level predators from demersal fish up to whales. This has no obvious equivalent in other marine ecosystems. In Antarctic offshore coastal and oceanic waters the greatest proportion of energy from the ecosystem is transferred to land directly through krill consumers, such as flying birds, penguins, and seals. Beside krill, the populations of fish in the Antarctic Ocean are the second most important element for higher predators, in particular the energy-rich pelagic Myctophidae in open waters and the pelagic Antarctic silver fish P. antarcticum in the high Antarctic zone. Although the occurrence of these pelagic fish inshore has been scarcely documented, their abundance in neritic waters could be higher than previously believed.

Information on the rates of incidental mortality of birds experienced by IUU vessels is extremely difficult to obtain. CCAMLR has, in the past, used data from the 1997 legitimate fishery, when a large number of birds were caught and when the implementation of mitigation measures was low, to approximate the IUU situation. This paper describes analyses undertaken using the 1997 data to refine the estimates of IUU bird catch rates for use in our analysis of the impact of IUU fishing in Subarea 48.3 (WG-FSA-02/4).

1. This paper describes a new method for estimating IUU catch of fish and birds. It utilises high quality, well-documented FPV (fisheries protection vessel) cruise data. It takes explicit account of both “seen” and “unseen” IUU fishing through a simulation model to arrive statistically rigorous estimates and confidence intervals of fish and bird catch by IUU vessels. This method has not been used previously to estimate IUU activity in CCAMLR. We recommend its continued use in Subarea 48.3 and extension to other regions of the Antarctic.
2. Of the sources of information on IUU fishing, Fishery Protection Vessel (FPV) cruises are the most consistent and reliable. The track of the FPVs on their cruises to South Georgia covers all possible areas of fishing for toothfish in Subarea 48.3. The method uses data from FPV cruises in Subarea 48.3, and the encounters between FPVs and IUU fishing activity, to estimate the total number of days of IUU fishing that could occur during each year. For each IUU incident detected by the FPV, we calculated a theoretical maximum time over which this IUU activity could have occurred. This was the time that elapsed between the FPV cruises that were immediately prior to and immediately subsequent to the incident, where these prior and subsequent cruises had not detected that same IUU activity (i.e. the same vessel). In other words, for each IUU incident we know when it was seen, and the closest adjacent times in which it was not seen – the difference being the theoretical maximum time that the vessel can have been present.
3. This theoretical maximum time was converted to actual IUU fishing time using a simulation model. For each year, the model simulated 1000 IUU fishing incidents during the year, and from the known FPV cruise pattern calculated both the observed IUU activity and the known real IUU activity. We considered IUU activity to have been observed when the IUU vessel and the FPV vessel were in the same place at the same time. When this occurred, the FPV was assumed to detect IUU activity according to an “encounter probability”. The encounter probability was estimated from the known encounters of FPV with licensed vessels. Thus for each encounter between an IUU vessel and an FPV we obtained an estimate of total IUU fishing time.
4. The total annual IUU catch of toothfish and birds was calculated using a second simulation model. Subarea 48.3 was divided into 6 Areas for the purposes of calculation of fish and bird catch associated with IUU fishing. The catch rate of fish was calculated for each Area and each year using reported catch and effort data. The catch rate of birds was calculated separately for summer and winter using previously published CCAMLR observer data obtained in the early licensed fishery (1997) when few vessels used mitigation measures. For each of 10,000 simulations fish and bird catch rates were obtained randomly from parent distributions, for each IUU-FPV incident.
5. Three years were analysed, 1998/99, 1999/00 and 2000/01. Each year covered fully the period 1 October – 30 September, thus including one summer and one winter period. The estimated total toothfish catch attributable to IUU fishing was 667 t, 1015 t and 196 t in 1998/99, 1999/00 and 2000/01 respectively (a total over the three years of 1879 t). The estimated total bird catch was 574 birds, 2200 birds and 544 birds respectively. 95% confidence limits were calculated to be 41-1778, 472-1744 and 23-481 respectively for fish and 122-1823, 825-5422 and 110-1813 respectively for birds... [Please contact the Secretariat for the full abstract.]

Analysis of the fishing fleet operation is one of preconditions of krill fishery small-scale management units determination. In this work the available data of haul by haul catch statistics for the Soviet krill fishery in subdivision 48.3 for 1986-1980 (15 thousand hauls) were analyzed. During the fishing season from April to September two basic fishing grounds with a quazi-stationary boundary between them located at 37-37 30’ W have been distinguished. These fishing grounds are formed along the outside periphery of the doubling off- Island current of anticyclone pattern at the points of this current contact with the Weddell sea water flow (the eastern ground) and the Antarctic circumpolar current (the western ground). Temporal-spatial variability of these grounds has been analyzed. The eastern fishing ground existed for a longer time period - basically from April to August, while the western ground - from August to September (in some years from June to September). The third fishing ground is distinguished in the area of underwater elevation formed by Shag Rocks in the Antarctic Circumpolar Current meander.
On the basis of the materials presented some aspects of krill fishery and krill consuming animals interrelations were considered and the conclusion was made about possible baselessness of the hypothesis of competition between these species for krill resources.

The purpose of this paper was estimating commercial fleet impact on krill population in different months over 1987-1990 fishing seasons, during which the Soviet fleet’s yields from Subareas 48.2 and 48.3 amounted to at least 95% of total catch. The calculations were based on the Soviet fleet haul-by-haul data using a model of probabilistic-statistical theory of fishery systems developed in the AtlantNIRO. Intensity of commercial fleet impact on krill population, on biomass and density of krill aggregated in the fishing grounds was assessed basing on 22800 haul data. The analysis of Soviet fleet operation during the seasons of its largest fishing pressing shows no fishing effect on the krill stock and, consequently, on krill-dependent predators. Krill fishery, neither by the removal value nor by intensity, was competitive with dependent predators for the krill resource. In this case, a certain spatial overlap of the ecological niche of dependent species and the fishery has taken place rather than functional overlap.

The Ross Sea is a well-defined embayment of Antarctica about the size of southern Europe, bounded by Victoria Land to the west; King Edward VII Peninsula, Marie Byrd Land, to the east; the Ross Ice Shelf to the south; and the Southern Ocean, Pacific Sector, to the north. Its waters are composed of two related biotic systems: the Ross Sea Shelf Ecosystem (RSShE) and the Ross Sea Slope Ecosystem (RSSlE). The RSShE is the last Large Marine Ecosystems on Earth (except the Weddell Sea) that has escaped direct anthropogenic alteration; the RSSlE, similar to all of Earth’s other marine ecosystems, has lost its large baleen whales but otherwise is intact. A huge multidisciplinary, international scientific effort has been invested in studies of the geology, physics and biology of the Ross Sea over the past 45 years. In particular the activities of the US, NZ and Italian Antarctic programs have been a model of international scientific cooperation and collaboration. The successful result is an incredible wealth of knowledge, including long-term biological data sets, not available anywhere else in the Antarctic, that have documented clear signals of climate forcing, as well as top-down influences not confused by human exploitation or activity. Ironically, much remains unknown about how these ecosystems function. The Ross Sea is off limits to mineral extraction, but pressures on its biological resources are growing. The economic value of the resources should be weighed against the value of the system as a unique scientific resource. The Ross Sea represents an unparalleled natural laboratory in which the results of different fishery management strategies can be modeled in the context of short-term and decadal variation in biological populations, with these models applied elsewhere in the Southern Ocean and the World.