Chapter IV — International 



The principal elements of the National Marine 

 Fisheries Service's directed research program are (1) 

 shipboard studies to document and monitor changes in 

 krill distribution, abundance, and age structure, and 

 related oceanographic conditions in the South Shetland 

 Islands area (Elephant, King George, and Livingston 

 Islands); (2) bottom trawl surveys to assess and 

 monitor the distribution and abundance of bottom fish 

 in the area; and (3) land-based studies of penguins and 

 pinnipeds that could be affected indirectly by krill 

 harvesting. Additional land-based studies of penguins 

 are carried out cooperatively with National Science 

 Foundation grantees on Torgersen Island, adjacent to 

 Palmer Station on Anvers Island. 



As in 1996 and 1997 the ship-based studies were 

 conducted in 1998 aboard the Russian research vessel 

 R/V Yuzhmorgeologiya, chartered by the Service. 

 The studies were done between early January and 

 early April. Krill density estimates in the Elephant 

 Island area have been derived from the survey data 

 for the 1992-1998 austral summers, excluding 1993. 

 This time series suggests a six-year periodicity in krill 

 density around Elephant Island and indicates rapid 

 declines in density in 1992 and 1998 and gradual 

 increases from 1994 through 1997. The krill popula- 

 tion reached a seven-year low in 1994 and a seven- 

 year high in 1997. Additional data will be required to 

 corroborate the apparent cycle. 



Forty-five fish species were caught and processed 

 in 1998 from 74 bottom trawls. The trawls were 

 done at stations around Elephant Island and the lower 

 South Shetland Islands. Species caught in substantial 

 numbers included Gobinotothen gibberifrons, Champ- 

 socephalus gunnari, Notothenia coriiceps, Chaenoce- 

 phalus aceratus, Chionodraco rastrospinosus, Lepido- 

 notothen squamifrons, Gymnoscopelus nicholsi, 

 Lepidonotothen larseni, Lepidonotothen nudifrons, and 

 Elect rona antarctica. 



The land-based studies of penguins and pinnipeds 

 were done in 1998 at Cape Shirreff on Livingston 

 Island. Previously, the program included land-based 

 studies at Seal Island, a small island off the northwest 

 coast of Elephant Island. Except for short-term site 

 visits, research at Seal Island was discontinued in 

 1997 because of the possibility of landslides destroy- 

 ing the support facilities. 



Studies of penguins and pinnipeds were conducted 

 at Cape Shirreff from 28 November 1997 to 28 

 February 1998. This was the first fall season of 

 penguin research at the Cape and comparisons with 

 prior years thus are not possible. Based on mean 

 breeding success at Admiralty Bay, approximately 140 

 km (87 miles) northeast on King George Island, the 

 chinstrap penguin population at Cape Shirreff had 

 average breeding success and the gentoo penguin 

 population above average breeding success during the 

 1997-1998 breeding season. Both chinstrap and 

 gentoo penguins ate primarily krill 31-45 mm in 

 length. Fish were noted in about one-third of all 

 chinstrap penguins and nearly all gentoo penguin 

 stomach samples. Chinstrap penguin foraging trip 

 durations were bimodals with 8- to 10-hour trips 

 alternating with 20- to 24-hour trips. 



A total of 7,748 Antarctic fur seal pups was born 

 at Cape Shirreff and the adjacent San Telmo Islands 

 during the 1997-1998 breeding season. This was a 

 14.1 percent decrease from the 9,015 counted in 

 1996-1997. At-sea foraging trips of lactating female 

 fur seals averaged 4.6 days. The mean distance 

 traveled was 98 km (61 miles) (s.d. = 24.9 km [15.5 

 miles]). A total of 53 scat and enema samples was 

 collected from fur seals for diet studies: 42 of these 

 samples contained identifiable hard parts (fish bone, 

 krill chitin, or squid beaks). Fish, krill, and squid 

 composed 61.9 percent, 57.2 percent, and 14.3 

 percent of the samples, respectively. Milk samples 

 were collected from 68 lactating females for fatty-acid 

 signature analysis to infer diet. Two fur seals tagged 

 at other sites were observed during the season at Cape 

 Shirreff; both were females tagged at Seal Island. 



Studies of Adelie penguins were conducted at 

 Torgersen Island, near Palmer Station, from 1 Octo- 

 ber 1997 through 4 April 1998. The number of 

 breeding pairs was essentially the same as the number 

 in 1996-1997. Breeding success was up slightly, with 

 an average of 1.58 chicks creched per pair, compared 

 with 1.47 in 1996-1997. Conversely, there was a 

 slight decrease in the proportion of two-chick broods. 

 The average fledgling weight of chicks was unchanged 

 from the previous year. 



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