CCAMLR

The paper introduces several approaches to assessment of hydrological situation in the Atlantic sector of the Southern Ocean (the South-West Atlantic). The analysis of the SST maps suggests that hydrological factors depend on the intensity of two currents, the Antarctic Circumpolar Current and the Falkland current The paper shows correlation between a certain hydrological situation and fishing for squid Illex argentinus.

In the austral summer of 1995/96, 25 southern elephant seals, Mirounga leonina, were stomach lavaged at Stranger Point, King George Island, South Shetland Islands. Cephalopod remains were present in 72% of the individuals sampled (n=18). Seven species of squid and 3 of octopus were identified. Overall, the squid species Psychroteuthis glacialis was by far the most important prey in terms of numbers (77%), biomass (80.8%) and frequency of occurrence (94.4%). Next in importance in terms of mass in the diet of females was the squid Alluroteuthis antarcticus (7%) whereas the octopodid Pareledone charcoti was in the diet of males (13.2%). Females preyed on a wider variety of squid taxa than males (7 vs. 3) but octopodids occurred only in stomach contents from males. The predominance of P. glacialis in the prey of the South Shetland elephant seals can be explained by the southerly location of the foraging areas of this population compared to South Georgia, Heard and Macquarie Islands, where the diet of Southern elephant seals has previously been analyzed. P. glacialis is the predominant squid in waters close to the Antarctic continent.

We requested data and information for further developing draft standard methods for recording sea-ice cover viewed from a CEMP site (Index F1), local weather at a CEMP site (Index F3) and snow cover at a CEMP site (Index F4). The information at hand was reviewed, and a revised approach to finalising the methodology for calculating these indices is proposed.

Work undertaken during the intersessional period has enabled better use of the krill fishery data, and a comparison between the three existing indices of fishery-krill-predator overlap used by CCAMLR (catch in the Critical Period and Distance [CPD], Agnew-Phegan index, and Realised Potential Overlap [RPO]) and the Schroeder index. The Agnew-Phegan and Schroeder indices were also compared at nine levels of spatio-temporal resolution and using normal, exponential and uniform foraging distributions.
Only catch in the CPD can presently be used to estimate overlap in areas other than Subarea 48.1. The catch in the CPD and the Agnew-Phegan index were closely correlated, as were the RPO and Schroeder index. All indices exhibited similar broad inter-annual trends over the period 1983 to 1998, indicating reduced overlap in Subarea 48.1 after 1990. The RPO and Schroeder index indicated a greater increase in the level of overlap in recent years (1995-98) than estimated with either the catch in the CPD or the Agnew-Phegan index. The type of foraging distribution and level of spatio-temporal resolution produced small difference in the values of the Agnew-Phegan and Schroeder indices, but had little influence on inter-annual trends. Increasing the level of resolution of the model, and in particular the spatial resolution, resulted in lower overlap between the krill fishery and the krill predators, and lower values of both the Agnew-Phegan and Schroeder indices.

The CCAMLR Ecosystem Monitoring Program uses indices derived from data on indicator species and the environment collected by standard methods within the three Integrated Study Regions of the Convention Area. Standardised index values are re-calculated each year as new data become available, and trends and anomalies in these data are presented.