655 



Consumption of Pacific herring iCIupea pallasi) 

 ^99^ l>y greenling (Hexagrammidae) 

 in Prince William Sounds Alaska 



Christopher N. Rooper 



Lewis J. Haldorson 



Juneau Center for Fisheries and Ocean Sciences 



University of Alaska Fairbanks 



11120 Glacier Hwy, Juneau, Alaska 99801 



Present address (for C N Rooper: Fishery Sciences Building 



Box 355020 



University of Washington 



Seattle, Washington 98195 

 E-mail address (for C- N Rooper) rooperig'fish Washington edu 



Predation is an important process reg- 

 ulating egg sui'vival in marine systems 

 (Bailey and Houde, 1989). Pacific her- 

 ring iClupea pallasi) spawn demersal 

 adherent eggs on shallow subtidal and 

 intertidal substrates. Consequently, 

 their eggs are available to a variety 

 of predators throughout incubation. 

 Documented predators of herring eggs 

 include birds, invertebrates, marine 

 mammals, and fish (Palsson, 1984). 

 Avian predators were responsible for 

 over 957c of the herring eggs lost in 

 the intertidal zone in Holmes Harbor, 

 Washington, in 1946 (Cleaver and Fra- 

 nett, 1946), 39% of the intertidal her- 

 ring eggs lost on the west coast of 

 Vancouver Island from 1947 to 1950 

 (Outram. 1958), and 70'~'r of the herring 

 eggs lost in Yaquina Bay, Oregon, in 

 1970 ( Steinfeld, 1971). Estimates of egg 

 predation by birds at two sites in Brit- 

 ish Columbia in 1988 and 1989 were 

 3.0^/f and 3.5'7f of the total eggs depos- 

 ited by herring (Haegele and Schwei- 

 gert, 1989; 1991). 



Much less is known about the effects 

 of other predators because studies to 

 quantify Pacific herring egg loss from 

 predators other than birds have been 

 rare. In Barkeley Sound, British Col- 

 umbia, predation by invertebrates 

 accounted for IS.OVf of the total herring 

 eggs deposited, whereas gray whales 

 consumed S.O'/r of the total eggs depos- 

 ited (Haegele and Schweigert, 1989). 

 In 1989, herring egg loss due to epiben- 

 thic invertebrates was 4.1% of the total 

 eggs spawned in Georgia Strait, Brit- 



ish Columbia (Haegele and Schweigert, 

 1991). 



Fish predation on Pacific herring 

 eggs has not been studied in the 

 northeast Pacific, although some studies 

 have been done on the deeper-spawn- 

 ing Atlantic herring (Clupea haren- 

 gus). Historically, abundance of North 

 Sea haddock {Melanogrammus aeglefi- 

 nils) and saithe (Pollachius virens) with 

 stomachs containing Atlantic herring 

 eggs were used as indicators of the con- 

 centrations of herring eggs (Hempel 

 and Hempel, 1971); in years of light 

 spawning, cod and haddock can con- 

 sume up to 60% of the total eggs depos- 

 ited.^ Stomachs of sand eels (Amrnodytes 

 marinus) have been observed to be full 

 of Atlantic herring eggs (Rankine and 

 Morrison, 1989), and perch [Perca flu- 

 viatilis) has been found to be the most 

 important consumer of herring eggs in 

 the Archipelago Sea (Rajasilta et al., 

 1993 ). For Atlantic herring off the coast 

 of Norway, egg loss due to haddock con- 

 sumption has been estimated at 4.2% of 

 the total eggs spawned (Toreson. 1991). 

 Total Atlantic herring egg loss due to 

 consumption by winter flounder iPseu- 

 dopleiironectes americanus ) was at least 

 7% of the total egg abundance at a site 

 in the Northwest Atlantic (Tibbo et al, 

 1963). 



Johannessen.A. 1980. Predation on her- 

 ring [Clupea harengus) eggs and young 

 larvae. International Council for the 

 Exploration of the Sea. Council Meeting/ 

 1980, H:.33. 12 p. 



Lack of knowledge about fish preda- 

 tion on Pacific herring eggs and the 

 importance of herring as a forage fish 

 in the Northeast Pacific Ocean, led 

 us to study predation on herring eggs 

 in Prince William Sound, Alaska. The 

 objective of our study was to estimate 

 total consumption of herring eggs by 

 some fish predators with the Elliot-Pers- 

 son model (Elliot and Persson, 1978). 



Materials and methods 



Our study was conducted after her- 

 ring spawning was completed on north- 

 ern Montague Island in Prince William 

 Sound, Alaska (Fig. 1), during late 

 April and early May, 1995. Two vari- 

 able mesh gill nets, 30.5 m long and 2.4 

 m deep, were used to collect fish near 

 incubating herring eggs in the subtidal 

 and intertidal zones at eight transects. 

 Stretched-mesh sizes ranged from 2.5 

 to 12.7 cm. Panels of same-size mesh 

 were equal length and depth (6.1 m x 

 2.4 m). and a total of five panels per net 

 were used. A standardized fishing plan 

 was carried out from one to three tran- 

 sects per day. Two nets were set at the 

 bottom parallel to the shoreline at each 

 transect. Depths fished depended on 

 tide stage; at high tide, depths fished 

 were 0.0 m and -3.0 m, whereas at low 

 tide, depths fished were -1.5 m and 

 -3.0 m in relation to mean low water. 

 Logistical constraints limited fishing to 

 one series of gillnet samples centered 

 around the daylight high tide, and one 

 series of samples centered around the 

 daylight low tide. Each series consisted 

 of three one-hour sets of the two nets, 

 for a total of six gillnet sets over each 

 tide stage, and a total of 96 sets equally 

 spread over the eight transects. 



Fish captured were identified by spe- 

 cies and measured for fork length. Time 

 of catch, net soak time, and tide stage 

 were also recorded for each fish. Fish 

 stomachs were removed and preserved 

 in \Q9( buffered formalin. Stomach con- 

 tents were categorized by type of prey 

 (herring eggs, vegetation, crustaceans, 

 etc. ) and weighed to the nearest 0.01 g. 

 Wet weights of each group of stomach 

 contents were recorded, and herring 

 eggs were subsampled to determine the 



Manuscript accepted 1 December 1999. 

 Fish. Bull. 98:655-659 (2000). 



