Research Document 1997/74
A Biological Review of the Commercial Diadromous Fisheries of Prince Edward Island
By D.K. Cairns
Abstract
Prince Edward Island, with its shallow bays, broad estuaries, and short rivers, contains an abundance of favourable habitat for diadromous fishes. PEI's commercial diadromous species are the American eel (Anguilla rostrata), gaspereau, (Alosa aestivalis and A. pseudoharengus), Atlantic silverside (Menidia menidia), rainbow smelt (Osmerus mordax), American shad (Alosa sapidissima) Atlantic tomcod (Microgadus tomcod) and Atlantic sturgeon (Acipenser oxyrthynchus).
Eels are fished commercially in spring by spearing and in fall by trap-nets, and recreationally by spearing through the ice. Reported landings have fallen by a factor of ten in the last decade. Catch rates in 1996, recorded by seven logbook fishermen, averaged 0.37 kg/trap-day. Electrofishing surveys on the Morell River suggest that eel densities have fallen sharply on that system since the 1970s and 1980s, but eel counts at Leards fishway on the same river fail to confirm a decline. Industry sources are unanimous that eel abundance had decreased, but current data are not sufficient to distinguish between recruitment reductions or growth overfishing as possible reasons for the decline.
Gaspereau are fished by commercial licence-holders authorized to sell to others and by bait licence-holders who are permitted to catch gaspereau as bait for their own use. Both fisheries operate during the spring spawning run. Gaspereau landings in PEI are not known because catches used for bait are usually not registered with official statistics. The one available catch rate time series suggests a sustainable fishery at that site. However, this does not necessarily mean that the resource is healthy overall because rivers probably have separate stocks which can vary independently of each other. Given the sparseness of information on PEI's gaspereau resource, a cautious approach to management is warranted.
Silversides are fished by trap-net in the fall, primarily in eastern PEI. Sticklebacks are commonly caught in silverside gear, and often force the suspension of fisheries because stickleback bycatches are not acceptable to buyers. Thus sticklebacks may provide an ecological refuge that reduces the risk that silversides will be overfished. Similarity between catch rates recorded in 1975 and 1995-1996 suggest that PEI's silverside fishery is sustainable.
Smelts are fished commercially in fall and winter by box and bag nets and by gillnets. They are also fished recreationally by spear, gillnet, and dipnet. Reported commercial landings in 1996 were 98 tons. Harvest by spearing, the main recreational gear, was estimated as 4.1 tons, using data from 1995 and 1997. A catch rate time series from Prince County suggests that the smelt fishery is sustainable at the site, but catch rates are unavailable from other areas. The PEI smelt fishery should be managed with caution.
There is no directed fishery for shad on PEI and no bycatch is recorded in most years. Substantial catches were taken in cod gillnets in 1991 and 1992. Tomcod is not subject to a directed fishery on PEI, but the species is regularly taken in the smelt fishery. Reported landings in the past several years are a small fraction those recorded in the 1970s, but the cause of this decline is not known. Atlantic sturgeon is taken sporadically and incidentally.
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