Research Document 1998/30
Status of Atlantic salmon stocks of southwest New Brunswick, 1996
By T. L. Marshall, R. Jones, and C. J. Harvey
Abstract
Total one-sea-winter (1SW) returns (3,255) and multi-sea-winter (MSW) returns (1,971) destined for above Mactaquac in 1997 were the lowest in 28 years of record. Hatchery-origin fish comprised 89% of 1SW and 43% of MSW fish, the highest percentages of record. Return rates for hatchery-released smolts were 0.56 (1SW) and 0.19 (MSW), i.e., less than those of 1996 but similar to other low rates in the 1990s. Spawners numbered 2,742 1SW fish and only 1,340 MSW salmon, 56% and 27% of the respective requirements. Egg deposition (53% from wild fish) was 30% of requirement; the requirement has not been met since 1985.
Below Mactaquac, counts at the Nashwaak River fence contributed to an estimated return of 370 1SW and 366 MSW salmon. Nearly all fish escaped to spawn thereby contributing to 18% of respective 1SW and MSW conservation requirements. An egg deposition of 23% of requirement was the lowest since operation of the fence recommenced in 1993. Counts at a fence in the headwaters of the Kennebecasis River suggested an escapement above that point of 76 1SW and 45 MSW salmon and a resultant egg deposition of about 35% of conservation requirement. Redd counts on an 11.75 km stretch of the upper mainstem Hammond River were about "average" for the 15 year dataset. Egg deposition within those redds was estimated to be 163% of the requirement for the stretch.
Of 178 salmon captured in the Magaguadavic River trap, 119 (inc. some post smolts) were deemed of aquaculture origins and denied access to the river. Wild and hatchery (escaped from private hatcheries on the river) fish numbered 35 1SW and 24 MSW salmon. After accidental mortalities, escapement resulted in an egg deposition of about 12% of requirement, the lowest of a 10-year record. Salmon ascending the St. Croix River at Milltown numbered 70 fish of which 27 were of aquaculture origins. Egg deposition was about 2% of requirement and divided between the river and Mactaquac hatchery.
1SW returns destined for Mactaquac in 1998 chould number 5,800 (2,400-9,700) fish and thereby exceed the 4,900 1SW conservation requirement. The majority of the returns will be of hatchery origin - either smolts released directly from Mactaquac or age-0+ fish released upriver of Mactaquac in 1994 and 1995. MSW returns destined for Mactaquac in 1998 could number 1,500 fish (700-2,100), or 14%-43% of the 4,900 MSW conservation requirement above Mactaquac. In total, it is highly unlikely that returns will provide one-half of conservation egg requirements.
Below Mactaquac, forecasted returns to the Nashwaak River fence may be as few as 320 (110-1,200) 1SW and 100 (50-130) MSW fish, i.e., equivalent to less than 10% of egg conservation requirements. Returns to other assessed Saint John River tributaries below Mactaquac and rivers flowing into Passamaquoddy Bay in 1998 are not expected to exceed either the numbers or proportionate achievement of conservation requirements experienced in 1997.
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