Assessing estuaries as stopover habitats for juvenile Pacific salmon

Abstract

Habitats along migratory routes may provide key resources for migratory species (e.g. stopover habitat). For example, migratory juvenile salmon transit through estuaries on their way from freshwaters out to the ocean, but they may also reside and feed in these habitats. Here we examined the amount of time that juvenile salmon feed and reside in the estuary of the Skeena River (British Columbia, Canada), the second-largest salmon-bearing watershed in Canada. We implemented a novel application of stable isotopes of sulfur, carbon, and nitrogen as clocks to estimate the days since estuary entry. Salmon estuary residency varied across species; 25% of individuals spent at least 33, 22, 30, and 5 d in the estuary for Chinook Oncorhynchus tshawytscha, coho O. kisutch, pink O. gorbuscha, and sockeye salmon O. nerka, respectively. Larger pink and Chinook salmon resided in the estuary for longer durations, growing at an estimated 0.2 and 0.5 mm d −1 , respectively, evidence that estuary residency provides growth opportunities. A negative relationship between size and estuary residency in coho salmon suggests the potential existence of an estuary fry life history. Genetic stock assignment indicated that different populations of sockeye salmon may reside in the estuary for different amounts of time. Collectively, these results reveal that estuaries can represent stopover habitats for salmon, and that the extent varies across salmon species and populations. These data address a knowledge gap in assessment of environmental risks of proposed industrial developments. This study indicates the importance of considering the fundamental nature of habitats through which migratory species move.

Phenological Diversity of Salmon Smolt Migration Timing within a Large Watershed

“…), but different populations may utilize estuaries for varying periods of time (Moore et al. ). Other studies have found that smaller and ocean‐type Sockeye Salmon may inhabit estuaries for a longer period of time.…”

“…; Moore et al. ). The trawl, which was 18 m long with a 5‐ × 4.6‐m opening, was fished from a chartered gill‐net vessel, HMV Pacific Coast , and was towed for a targeted duration of approximately 15 min per set.…”

So you want to change the world?

“…Jonathan Moore, a coastal scientist at Simon Fraser University in Vancouver, Canada, spent four years tallying up the social and environmental havoc that would be caused by a liquid natural-gas terminal on the northern coast of British Columbia: it would disrupt habitats that support salmon relied on by 11 First Nations groups over an area the size of Switzerland, his team found. Although Moore and his colleagues have published in the peer-reviewed literature 9 , been covered by hundreds of media outlets and met with communities and policymakers, the terminal was granted government approval by a regulatory review process that many Canadian scientists find lacking.…”

Towards linking environmental law and science

“…Indigenous and environmental lawyers and scientists are currently collaborating on briefs and testimony to a Parliamentary Committee studying the Oceans Act's Marine Protected Areas regime, making the case for amendments that would reflect scientific guidance on effective marine protected areas (Nowlan and Watson 2017). As another example, during the Parliamentary review of the federal Fisheries Act, environmental lawyers cited research on fish habitat impacts in the Skeena estuary from proposed energy development projects to bolster their arguments for the need for stronger habitat protection provisions in the law Moore et al 2016;Nowlan 2016). As these examples illustrate, legal researchers and practitioners can connect with scientists working in their area of interest for collaboration, and collectively they can communicate needs to improve and strengthen environmental law.…”

“…FACETS | 2018 | 3: 375-391 | DOI: 10.1139/facets-2017-0106 377 facetsjournal.com assessment of a large energy industrial development in the Skeena River estuary (British Columbia, Canada), researchers discovered that the project was proposed for a location that was particularly important for young migratory salmon and that risks of the project were under-assessed Moore et al 2015Moore et al , 2016. This science was submitted as evidence by First Nations' legal teams during environmental assessment comment periods and consultative processes and likely contributed to dialogue, negotiations, and project design modifications.…”