Three previous posts on the Bulkley steelhead catch and release study undertaken during the 2016 season pointed out a number of issues that no one integral to the study has shown any inclination to address. Silence has become the hallmark of the government people involved and the principle researchers dismissed my latest attempt to obtain a description of the project objectives and methods and any preliminary results that might be available with the comment:
“Sorry Bob – Can’t invest any more time into responding to your queries/critiques. I am reasonably confident there is nothing I can say that will make you appreciate the work we are doing or its value. You have your mind firmly made up regarding where the issues are.”
Indeed I have and I have outlined them here previously. To reiterate, both the commercial and, especially the First Nations fishery at Moricetown, have a far greater impact on Bulkley steelhead than fly fishermen working on the fish that didn’t get caught by those fisheries. (Arguably there is a fourth, the Department of Fisheries and Oceans’ test fishery that operates just upstream from the commercial fishing boundary in the intertidal reaches of the lower Skeena.) What defensible logic is there in focusing only on the least impactful of the three fisheries?
Now, out of the blue, comes a publication that crystallizes my concerns and frustrations. Kudos to my friends at Watershed Watch (watershedwatch.org) for passing this along. Here’s the formal citation:
Amy K. Teffer, Scott G. Hinch, Kristi M. Miller, David A. Patterson, Anthony P. Farrell, Steven J. Cooke, Arthur L. Bass, Petra Szekeres, Francis Juanes; Capture severity, infectious disease processes and sex influence post-release mortality of sockeye salmon bycatch. Conserv Physiol 2017; 5 (1): cox017. doi: 10.1093/conphys/cox017
Note that one of the authors of this paper is also one of the principles involved in the Bulkley study. The field research leading to this publication was conducted in July, 2013 so it is entirely reasonable to assume the results were well known long before the 2016 Bulkley study commenced.
The Abstract of the paper says about as much as needs to be said about the issues I’ve been harping on.
Bycatch is a common occurrence in heavily fished areas such as the Fraser River, British Columbia, where fisheries target returning adult Pacific salmon (Oncorhynchus spp.) en route to spawning grounds. The extent to which these encounters reduce fish survival through injury and physiological impairment depends on multiple factors including capture severity, river temperature and infectious agents. In an effort to characterize the mechanisms of post-release mortality and address fishery and managerial concerns regarding specific regulations, wild-caught Early Stuart sockeye salmon (Oncorhynchus nerka) were exposed to either mild (20 s) or severe (20 min) gillnet entanglement and then held at ecologically relevant temperatures throughout their period of river migration (mid–late July) and spawning (early August). Individuals were biopsy sampled immediately after entanglement and at death to measure indicators of stress and immunity, and the infection intensity of 44 potential pathogens. Biopsy alone increased mortality (males: 33%, females: 60%) when compared with non-biopsied controls (males: 7%, females: 15%), indicating high sensitivity to any handling during river migration, especially among females. Mortality did not occur until 5–10 days after entanglement, with severe entanglement resulting in the greatest mortality (males: 62%, females: 90%), followed by mild entanglement (males: 44%, females: 70%). Infection intensities of Flavobacterium psychrophilum and Ceratonova shasta measured at death were greater in fish that died sooner. Physiological indicators of host stress and immunity also differed depending on longevity, and indicated anaerobic metabolism, osmoregulatory failure and altered immune gene regulation in premature mortalities. Together, these results implicate latent effects of entanglement, especially among females, resulting in mortality days or weeks after release. Although any entanglement is potentially detrimental, reducing entanglement durations can improve post-release survival.
Okay, lets cut to the chase. This study is focused on sockeye, not steelhead but I’ll stand on the assumption the results are equally applicable. What those results are saying is steelhead released after being caught by a gill net will not contribute to the next generation at anywhere near the rate of their co-migrants that were not caught. Those experimental sockeye were captured 150 km and five days removed from the mouth of the Fraser River. If they had been captured in the transition zone between salt and fresh water where their physiological state is known to be more sensitive it isn’t unreasonable to conclude the post release observations would have been worse.
The influence of experimental treatments on post release observations reported in this study is important. With respect to the Bulkley study, I’ve stated consistently it is impossible to assess how much of the post release behaviour and performance of steelhead is related to the angling event and how much is related to all the experimental procedures that followed (i.e. the treatment effects). Here we have evidence entirely supportive of the position it is inappropriate to apply observations on experimental fish to the population of angler released steelhead in general.
Consider next the commercial gill net fishery at the mouth of the Skeena, that sensitive transition zone. The regulations pertaining to that fishery state:
“20 minute soak times: The maximum amount of time the net is allowed to be in the water from the time it is completely set to the time it begins to be retrieved is 20 minutes. Note that this “soak time” is designed to equal a 40 minute time from when the first portion of the net enters the water to the time when the last portion of the net leaves the water.”
The results of this Fraser sockeye study demonstrate clearly the devastating consequences of a 20 minute period of entanglement. If Skeena steelhead picked from a gill net and released were probably in the net for 20-40 minutes, what was their post release performance likely to be? Add to that there is virtually zero enforcement of those set time regulations and draw your own conclusions. Then think about that test fishery on the lower Skeena that sets for a full hour before beginning net retrieval. That fishery catches several hundred steelhead every year (some years well over 1000), about half of which are dead on arrival. Can the fate of those released somehow not reflect what has now been formally documented for those Fraser sockeye?
Next in line is Moricetown where the capture and treatment of steelhead has been demonstrated in spades on this site and elsewhere many times previously. Those Fraser sockeye results speak volumes about the consequences to steelhead of the mark and recapture population estimation “experiment” that has become a fact of life. Apart from the direct and indirect influence on individual fish, what does the ever expanding science on catch and release impacts say about the validity of any population estimates from the Moricetown program?
Is it starting to become apparent studying the consequences of a single catch and release event for an angled steelhead is not the highest priority for Bulkley or Skeena steelhead in general? If not, what will it take?