CCAMLR

An assessment of the environmental processes influencing variability in the recruitment and density of Antarctic krill (Euphausia superba DANA) is important as variability in krill stocks affects the Antarctic marine ecosystem as a whole. Naganobu et al. (1999) had assessed variability in krill recruitment and density in the Antarctic Peninsula area with an environmental factor; strength of westerly winds (westerlies) determined from sea-level pressure differences across the Drake Passage, between Rio Gallegos, Argentina, and Base Esperanza, at the tip of the Antarctic Peninsula during 1982-1998. Fluctuations in the westerlies across the Drake Passage were referred to as the Drake Passage Oscillation Index (DPOI). They found significant correlations between krill recruitment and DPOI. Additionally, we calculated a time series of DPOI from January 1952 to March 2006. In addition, we tried to draw a comparison between DPOI and oceanographic condition using CTD data during 1990-2004. As a result, DPOI had a strong correlation with the averaged temperature of the surface layer (ITEM-200). DPOI suggests influence on the variability of oceanic condition and thus for Antarctic krill ecosystem.

Penguins may exhibit plasticity in their diving and foraging behaviors in response to changes in prey availability. Chinstrap penguins are dependent predators of Antarctic krill in the Scotia Sea region. Both the sizes of krill found in penguin diets and acoustic estimates of krill biomass have fluctuated in recent years. We therefore examined the diet of chinstrap penguins at Livingston Island, South Shetland Islands in relation to their diving and foraging behavior using time-depth recorders (TDRs) over five seasons: 2002-06. When krill were smaller, chinstrap penguins often exhibited a shift to deep dives after sundown, and then resumed their shallower pattern at sunrise. These nighttime dives were unexpectedly deep (up to 110m) and mean nighttime depths sometimes exceeded those from the daytime. The average annual size of krill was negatively correlated to the number of penguins foraging on fish, mean nighttime dive depths, and the proportion of foraging trips occurring overnight. Based on these patterns, we suggest that when krill were small, penguins foraged more on myctophid fish. The average krill size was negatively correlated to the time chinstrap penguins spent foraging which suggests that penguins made this switch to fish with a cost: more time was spent at sea foraging.

Results of the survey of entanglements of Antarctic fur seals at Bird Island, South Georgia for the 17th consecutive winter (2006) and 19th consecutive summer (2006/07) are reported here. A total of 41 winter entanglements were observed in the reporting period compared to 2 observed in the previous winter. This is the second highest winter total since records began in 1990 (the highest was in 1992 when 97 entanglements where reported). The number of entanglements seen during the summer period was 17, an increase of 112.5% over the previous summer, and the highest since 2001/02. During the winter 49% of entanglements were classed as severe (cutting through the skin) or very severe (breaking through both the skin and underlying fat layer). Over the summer period 18% of entanglements were classed as severe or very severe. Synthetic string/rope was the most commonly found item forming neck collars (37% and 35% during winter and summer respectively). On 16 occasions the material was found to be a loop of rope similar to that shown in appendix three. Plastic packaging bands were the second most abundant material overall (28%), closely followed by fishing nets (26%). Juveniles (including sub-adults) were involved in 56% of all entanglements in winter and 53% in the summer. Overall females made up the majority of the sexed individuals in all age classes (43%) compared to males (33%) and the remainder unknown. The increase in the number of winter entanglements (41) and animals with severe wounding (20) was the highest recorded in 14 years, whilst the recent escalation in summer entanglements since 2004/05 is also a cause for concern.

A new move-on rule was introduced in Conservation Measure 33-03 at CCAMLR-XXIV regarding the by-catch limit of new and exploratory fisheries. This move-on rule requires fishing to cease when the catch of Macrourus spp. by a single vessel exceeds 16% of its Dissostichus spp. catch in any two 10-day periods in a single SSRU (CM 33-03 paragraph 5). The interval of the “10-day period” was defined arbitrarily and sometimes does not fit the practical fisheries operations in the harsh Antarctic environment. Japan therefore proposes three options to modify the Conservation Measure in order to solve the problem.

This paper presents a revised analysis of krill biomass for Division 58.4.2 using data from the 2006 Australian survey and based on the most recent advice from WG-EMM.