ESTIMATING TOTAL MORTALITIES ON ENDANGERED CHINOOK
February 6, 2020
Abstract Fisheries managers, First Nations, and stakeholders are becoming more aware that Fisheries Related Incidental Mortality (FRIM) can contribute significantly to Total Mortalities (TM) in fisheries. As a case study on one fishery, we examine potential FRIM and TMs in Spring and Summer Fraser River Chinook populations designated as ‘Endangered’ by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) (Table 1).
The South Coast Juan de Fuca recreational fishery encounters Spring and Summer Fraser River (42 and 52) Chinook from Southwest Vancouver Island to the mouth of the Fraser River (DFO fishery management areas 18,19,20,29,121). As the largest and oldest Chinook that return to the Fraser River, these fish are important to endangered Southern Resident killer whales and as a source of food for interior First Nations.
We apply the guidance provided in Patterson et al. (2017b) and interviews with anglers to identify risk factor ranges for Capture, Injury, Handling, and Predation Mortality. These are combined with drop-out mortality and a Monte Carlo simulation to estimate a range of FRIM. Other factors that may affect estimates of FRIM, such as the stock composition of releases, are also investigated.
Our results suggest that current methods for estimating FRIM employed by both DFO (15% x releases) and the Pacific Salmon Commission (PSC) Chinook Technical Committee (15% drop-out mortality on catch and 10% immediate mortality on releases) likely underestimate FRIM when compared to the Patterson et al. (2017b) approach.
In conclusion, we discuss management recommendations for improved monitoring and identify information needs in both this fishery and others that effect endangered chinook.
Conservation groups released information today that provides evidence that more endangered Fraser River Chinook were killed in fisheries last year than promised by Fisheries and Oceans Canada.
Despite a commitment to reduce Fraser spring and summer Chinook mortality to less than five per cent, recent analyses using the federal government’s own data suggest this limit was far exceeded and that a full fisheries closure would have allowed at least 25 per cent more endangered Chinook salmon to spawn. Last year marked the lowest return of Fraser River spring and summer Chinook on record: fewer than 14,500 reached their spawning grounds.
Fisheries and Oceans Canada lacks adequate monitoring to fully assess fishing mortality of Chinook, but for three of the 10 fishing areas, there is enough data to show that at least 4,000 spring and summer Fraser Chinook were killed. The number of spring and summer Fraser River Chinook that successfully made it to their spawning grounds in 2019 was less than 14,500 — the lowest number on record.
Read the press release and the backgrounder for more information.
The MCC recently submitted comments on the 2019/2020 Pacific Herring Integrated Fisheries and Management Plan, recommending considerations towards a “low risk” ecosystem based management fishery.
The growing public concern reflects a perspective that the fishery imposes too large a risk to herring populations and the associated ecosystem linkages than what is deemed appropriate through the lens of an ecosystem based fishery. Many of these concerns are the same ones that were raised over a decade ago.
The following recommendations are included in the letter:
Increase the lower reference point to reflect an ecosystem based conservation objective.
Lower the exploitation rate.
Plan for a lower biomass and harvest rate until validated with in-season management.
Assume there is a mechanism for persistent geographic population structure.
On August 22nd, the DFO released a new report examining broad scale trends in Pacific salmon. They found that species that spend more time in freshwater (chinook, coho, sockeye) are declining more than those that do not (chum, pink), in general.
At DFO’s first State of the Salmon meeting in 2018, scientists concluded that Canadian Pacific salmon and their ecosystems are already responding to climate change. Northeast Pacific Ocean warming trends and marine heatwaves like “The Blob” are affecting ocean food webs. British Columbia and Yukon air and water temperatures are increasing and precipitation patterns are changing, altering freshwater habitats. The effects of climate change in freshwater are compounded by natural and human-caused landscape change, which can lead to differences in hydrology, and increases in sediment loads and frequencies of landslides. These marine and freshwater ecosystem changes are impacting Pacific salmon at every stage of their life-cycle.
Some general patterns in Canadian Pacific salmon abundances are emerging, concurrent with climate and habitat changes. Chinook numbers are declining throughout their B.C. and Yukon range, and Sockeye and Coho numbers are declining, most notably at southern latitudes. Salmon that spend less time in freshwater, like Pink, Chum, river-type Sockeye, and ocean-type Chinook, are generally not exhibiting declines. These recent observations suggest that not all salmon are equally vulnerable to climate and habitat change.
Improving information on salmon vulnerability to changing climate and habitats will help ensure our fisheries management, salmon recovery, and habitat restoration actions are aligned to future salmon production and biodiversity. To accomplish this, we must integrate and develop new research across disciplines and organizations. One mechanism to improve integration of salmon-ecosystem science across organizations is the formation of a Pacific Salmon-Ecosystem Climate Consortium, which has been recently initiated by DFO’s State of the Salmon Program.
The MCC Salmon Subcommittee has released a letter to Fisheries and Oceans Canada with recommendations for monitoring in SC recreational fisheries. In summary, with management measures moving to non-retention of chinook in many areas, there are concerns around the Fisheries Related Incidental Mortality (FRIM) still being high and impacting stocks of concern like Fraser River 42/52 chinook. As the non-retention of chinook increases, total mortalities will decrease (e.g. some fish that would have been kept are now released) however FRIM will increase. Our recent discussion paper illustrates that new guidance for the derivation of FRIM suggests that estimates using current methodology from DFO and PSC managers may underestimate the actual FRIM in these fisheries, and likely by a large margin.
This letter calls for increased monitoring in recreational fisheries specifically in regards to genetic sampling of released fish, as well as kept chinook, so that managers can determine the stock composition of both released and kept chinook. Additionally the MCC is requesting that DFO incorporate the guidance provided by Patterson et al. (2017) in future FRIM and total mortality estimates.
The following figure shows that the median estimate of FRIM in the full non-retention scenario (bottom-left panel – based on 2018 catch and release data) is about 9000 using guidance from Patterson et al. (2017) – nearly 4-fold higher than DFO’s estimate and double that using PSC methods.
VANCOUVER — The federal government has announced commercial and recreational fishing restrictions in British Columbia as a way to conserve chinook salmon returning to the Fraser River this season.
The Fisheries Department’s regional director general Rebecca Reid says urgent protection measures include the closure of a commercial fishery involving seven endangered stocks.
Reid says an independent committee of wildlife experts and scientists conducted an assessment last November and determined seven chinook populations on the Fraser River are endangered, four are threatened and one is of special concern.
One area salmon was considered not at risk while three others were not assessed by the Committee on the Status of Endangered Wildlife in Canada.
Reid says harvest management measures alone won’t deal with declining numbers of chinook in recent years due to multiple factors including warming waters because of climate change and destruction of habitat that must be rebuilt.
VANCOUVER—The critically endangered southern resident killer whales may have more chinook salmon to eat this summer, as Fisheries and Oceans Canada announced stricter fishing quotas for British Columbia’s coast on Tuesday.
Fisheries and Oceans Canada — often called the Department of Fisheries and Oceans, or DFO — already reduced harvesting quotas for B.C. chinook by a third last summer, but staff admitted Tuesday that those measures have not been as effective as they hoped.
The DFO is now setting a new goal of reducing chinook salmon mortality to five per cent for 2019. The new restrictions are aimed specifically at protecting the Fraser chinook fisheries.
Current mortality levels for chinook returning to the Fraser River before July are closer to 20 per cent, according to Misty MacDuffee, wild salmon program co-ordinator at Raincoast Conservation Foundation. The southern resident orcas rely heavily on this specific cohort of fish, she said.
Ottawa has announced stronger measures to preserve endangered populations of Fraser River chinook salmon, placing new restrictions on commercial and recreational fishing.
Last year, the Department of Fisheries and Oceans aimed to restrict wild chinook harvesting across B.C. by 25 per cent to 35 per cent. But Rebecca Reid, DFO’s regional director general for the Pacific region, said these reductions were not enough to protect the rapidly declining salmon stocks.
“Unfortunately, we are at the point where bold action is required,” Ms. Reid said.
For the news release and backgrounder from DFO, visit here.
Fisheries management measures for the 2019 fishing season will include:
Commercial fishing: Commercial troll fisheries for Chinook will be closed until August 20 to avoid impacting Fraser Chinook stocks and to support conservation priorities.
Recreational fishing: The 2019 management measures for recreational fisheries where at risk Chinook stocks may be encountered are designed to maximize returns of these at risk Chinook to their spawning grounds. Opportunities to harvest Chinook will be provided later in the season to support the long-term viability of the recreational industry. The 2019 measures include:
Non-retention of Chinook in Southern BC (including West Coast Vancouver Island offshore, Johnstone Strait and Northern Strait of Georgia) until July 14; a daily limit of one (1) Chinook per person per day after July 15 until December 31.
Non-retention of Chinook in the Strait Juan de Fuca and Southern Strait of Georgia until July 31; retention of one (1) Chinook per person per day as of August 1until December 31.
West Coast Vancouver Island offshore areas will have non-retention of Chinook until July 14 followed by a limit of two (2) Chinook per day from July 15 to December 31. West Coast Vancouver Island inshore waters will remain at two (2) Chinook per day for the season once at-risk Chinook stocks have passed through, to support the long term viability of the salmon and of the recreational fishery.
Fraser River recreational fisheries will remain closed to salmon fishing until at least August 23, and opportunities will be informed by any other conservation issues (coho, steelhead, etc).
Retention of two (2) Chinook per day continues to be permitted in Northern BC and inshore areas of the West Coast of Vancouver Island. Other opportunities may be identified and announced in season where abundance permits.
An overall reduction in the total annual limit for Chinook that can be retained per person in a season from 30 fish to 10. Recreational fisheries for other species will continue. Please see the Department’s web-site for local regulations.
First Nations food, social and ceremonial fisheries: these fisheries, which have a constitutionally protected priority, will not commence until July 15 – concurrent with the opening of the recreational retention fishery.