Research Document - 2013/071
Inner Bay of Fundy (iBoF) Atlantic Salmon (Salmo salar) Marine Habitat: Proposal for Important Habitat
By T. L. Marshall
Abstract
The inner Bay of Fundy (iBoF) Atlantic salmon (Salmo salar) was listed as an endangered species under the Species at Risk Act (SARA) when it came into force in 2004. SARA requires the identification of critical habitat for endangered species. A Recovery Strategy for the iBoF salmon was developed and published on the SAR Public Registry in May 2010, but was only able to identify freshwater critical habitat areas. Because Atlantic salmon require both freshwater, estuaries, and marine habitat to complete their life cycle, the Strategy included a Schedule of Studies to help define additional critical habitat.
Previous documentation in support of the estuarine and marine habitats of iBoF salmon reviewed tagging, telemetry and trawling studies of iBoF post-smolts through 2008. The use of Bay habitats by returning/spawning salmon had been and continues to be based on captures of Carlin-tagged fish in now-closed commercial fisheries. These data represent a body of evidence indicating that some areas within the Bay have a long history of use by at least two life stages moving throughout most of the Bay during their marine phase. Unknown was the extent and proportion to which iBoF salmon smolts used the Bay as post-smolt nursery area, their area of occurrence October through winter and the wintering location of adults and reconditioning kelts. Hence, the probabilities of use for all habitat locations could not be estimated and therefore predicted with equal certainty as required under previous guidelines for the identification of Critical Habitat. Recently, however, the guidelines for the identification of critical habitat have been relaxed such that the absence of scientific certainty regarding the function of the Critical Habitat will not preclude its identification to the extent possible using the best available information.
This document reviews:
- information contributory to past evidence of extended use of the Bay by iBoF salmon,
- newly published analyses of the decade-old data from electronically tagged post-smolts and provides
- inferred temporal occupancy of estuarine and marine habitats through past smolt, post-smolt and adult monitoring activities and as well, relevant commercial and recreational catch data.
Overwintering habitat of all stages and summer habitats of distant migrating post-smolts and maturing adults of the iBoF salmon remain undocumented, although publication of the migration paths of several iBoF kelts tagged in November/December and May bearing 4- and 6-month duration pop-up satellite tags is expected to reveal their habitats and by corollary, perhaps those of post-smolts and maturing adults.
In the spirit of simplicity and to the extent possible, ‘important habitat’ is identified as the entire Bay of Fundy outward to the northern Gulf of Maine and the Canada-US boundary southward to latitude 43° 46’, May through October. The entire area can, however, be viewed as the sum of eight zones, each having a variation in function, features and attributes for the different life stages documented within. Most recommendations for research outlined in the 2010 Recovery Strategy remain relevant to the further identification of important habitat. The recommendation to further research the migratory behaviour of post-smolts using available geo-referenced data and the identification of the winter habitat of kelts, have been largely addressed but results for kelts are as yet unavailable.
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