Research Document 1997/27
Status of Atlamtic salmon stocks of southwest New-Brunswick, 1996
By T.L. Marshall, R. Jones, and T. Pettigrew
Abstract
Total one-sea-winter (1SW) returns (6,723) destined for above Mactaquac in 1996 were the highest since 1992. The wild component (20% of the total) was the lowest since 1972; hatchery-origin 1SW returns (80% of the total) were the highest since 1981. Multi-sea-winter (MSW) returns (3,321) increased from those of 1994-1995 but remained low. Hatchery-origin MSW fish (1,002; 30% of total) were the highest since 1984. Return rates for hatchery smolts were, in contrast to 1995, the highest of recent years. Spawners numbered 5,476 1SW and 2,518 MSW salmon, 112% and 51% of the respective new conservation requirements. Egg deposition (61% from wild fish) was 57% of the new requirement; the requirement has not been met since 1985
Below Mactaquac, counts at the Nashwaak fence contributed to an estimated return of 1,829 1SW and 657 MSW salmon, the highest values since monitoring there was re-instituted in 1993. Estimated spawners were 88% and 31% of respective new 1SW and MSW requirements. Egg depositions increased from the levels of 1993-1995 to 48% of the new requirement. Counts at a fence in the headwaters of the Kennebecasis River suggested an escapement above that point of 115 1SW and 63 MSW salmon with potential for egg deposition of 52% of requirement. Redd counts on an 11.75-km stretch of the upper main stem Hammond River were the highest since 1992. Egg deposition within those redds was estimated to be 341% of the requirement for the stretch.
External and scale characteristics of 222 1SW and 41 MSW salmon captured in the Magaguadavic River trap indicated that only 48 1SW and 21 MSW salmon were of wild (non-aquaculture) origin - the lowest of a 9-year record. Unlike 1995, aquaculture fish were released to spawn in the river. The effective female escapement (many aquaculture fish were determined to be immature) indicated that potential egg deposition was 18% of requirement; 41% of the eggs was of aquaculture-origin fish.
Salmon ascending the St. Croix River at Milltown numbered 152 fish of which only 21 were of aquaculture origins. An estimated egg deposition of 4% of requirement was double that of 1995. An additional 2% of requirement was taken for hatching and artificial rearing.
1SW returns destined for Mactaquac in 1997 should number 7,800-9,400 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 1993 and 1994. MSW returns destined for Mactaquac in 1997 could number 3,100- 3,600, i.e., 63%-73% of the 4,900 MSW conservation requirements above Mactaquac.
Qualitative forecasts of returns to the other assessed rivers of Southwest New Brunswick indicate that the proportions of conservation requirements (eggs) that will be met in 1997 are unlikely to exceed those levels observed in 1996.
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