Our Livini; Ri'soiirct'.s — Alaska 



341 



Today, more than 25 years after the discov- 

 ery of oil in Prudhoe Bay. it is hydrocarbon 

 resources, and not fish or wildlife, that most 

 Americans equate with Alaska's North Slope. 

 From national and statewide perspecti\es, 

 Arctic fisheries are of little significance in 

 tenns of total landings and economic worth. 

 But small, northern fisheries contribute to rural 

 economies and provide necessary sources of 

 protein for Alaska's Native people. As such, the 

 welfare of exploited fish populations and pro- 

 tection of regional lifestyles are dominant envi- 

 ronmental and sociological themes associated 

 with the industrialization of Arctic coastlines. 

 Fully one-third of adult Inupiat Eskimos parti- 

 cipate in subsistence fisheries. They capture 

 about 96.000 kg (210.000 lb) of fish annually, 

 an ainoLuit that rivals the yearly Native harvest 

 of bovvhead whales. Commercial fishermen 

 harvest another 40.000 fish in a fall-w inter fish- 

 ery. 



The continued development of the Prudhoe 

 Bay oilfields in Alaska required the construc- 

 tion of two solid-fill gravel causeways (West 

 Dock in 1974-75, e.xtended in 1976 and 1981: 

 Endicott Causeway in 1984-85) extending sev- 

 eral kilometers offshore (Fig. 1). These cause- 

 ways can cause transient changes in local fish 

 habitat. Biologists are concerned that fish pop- 

 ulations may be negatively affected when 

 causeway-induced changes in habitat quality, 

 quantity, or availability combine with regional 

 fishery removals. Because nearshore water cir- 

 culation is wind-driven, these changes vary 

 with wind speed, direction, and duration. 



Arctic Cisco (Coregonus autnmnalis). broad 

 whitefish (C. nusiis). least cisco (C scinlincUa). 

 and Dolly Varden char (Salveliniis malnui) are 

 the fish of primary concern. These anadromous 

 species have life cycles that include annual 

 migrations from winter habitats in fresh water 

 to summer feeding habitats in salt water. 



Summer habitats are in coastal environ- 

 ments, which are vulnerable to industrial devel- 

 opments. The species have adapted to Arctic 

 conditions through strategies that promote their 

 welfare, including complex migrations, vari- 

 able freshwater rearing periods, being long- 

 lived with late maturity, and having low recruit- 

 ment rates. 



Fish Monitoring 



Inventories offish habitats, populations, and 

 fisheries in the Alaska Beaufort Sea began in 

 earnest during the mid-1970"s. The construc- 

 tion of the West Dock and Endicott causeways 

 required environmental monitoring and other 

 research to evaluate the effects of these struc- 

 tures. The study area included Prudhoe Bay and 



120 km (75 mi) of adjacent coastline between 

 the Colville and Sagavanirktok river deltas 

 (Fig. 1). 



Biologists initiated fish-monitoring studies 

 around causeways in 198 1 . For monitoring they 

 incorporated common fishery techniques used 

 to estimate population health and size (Norton 

 1989; Benner and Middleton 1991). Their sam- 

 pling included live captures of fish along the 

 coast, standard biological measurements, and 

 physical assessments of fish habitat. They con- 

 ducted their fieldwork between June and mid- 

 September. Biologists have also compiled 

 annual fishery statistics from the Colville River 

 since 1967. 



We examined three data sets: season-aver- 

 aged catch rates: season-long estimates of pop- 

 ulation size from mark-recapture studies: and 

 effort-adjusted catch rates and total harvests 

 from the commercial fishery. Because sampling 

 effort varied each year, we derived coastal 

 indices of abundance from five permanent sta- 

 tions established in 1985. We based our counts 

 of small Arctic ciscoes and broad whitefish on 

 all available catch records. 



We defined groups of fish of the same 

 species that comprise the same age or size 

 ranges (called cohorts). For Arctic cisco and 

 broad whitefish: cohort I — age (young-of- 

 the-year), cohort II — age 1, cohort III — ages 2 

 and 3. and cohort IV — age 4 or older. For least 

 cisco: cohort I less than 180 mm (7.1 in) long 

 and cohort II at least 180 mm (7.1 in) long. For 

 Dolly Varden char: cohort I — less than 350 

 mm (13.8 in) long, and cohort II — at least 350 

 mm (13.8 in) long. 



Arctic Fish Species 



Arctic Cisco 



Biologists believe that Arctic cisco inhabiting 

 the central Alaskan Beaufort Sea originate in the 



Anadromous 

 Fish of the 

 Central 

 Alaska 

 Beaufort Sea 



by 



Lyman K. Thorsteinson 



National Biological 



Service 



William J. Wilson 



LGL Alaska Research 



Associates, Inc. 



Colville River 



Fig. 1. Prudhoe Bay study area stiowing West Dock and the Endicott Causeway, Alaska. 



