The expansion of mark-selective fisheries in mixed stock areas is complicating a decades-old method of tracking fisheries impacts across the West Coast, according to a recent report from the Pacific Salmon Commission.
Mark-selective fisheries require fishermen to release salmon with an intact adipose fin that indicates it was not produced in a hatchery. Most hatchery fish are marked by removing the fin on the fish’s back near the tail. This method has allowed maintaining fishing opportunities in an era of federal Endangered Species Act listings on salmon.
Many of these mark-selective fisheries occur in mixed stock areas: parts of the ocean and Puget Sound where both weak and strong salmon runs from various rivers intermingle before returning to their river of birth to spawn.
While the intention of these mark-selective fisheries is to allow for more fishing opportunity while not increasing impacts on weak natural runs in mixed stock areas, they undermine how fisheries are being managed coastwide.
One of the most important tools for studying how fisheries are working is the coded-wire tag program used by hatchery and fisheries managers in Alaska, Canada and the Pacific Northwest. Small metal tags are inserted into the snouts of fish, each with a code for the hatchery where the fish was produced. A lot of data can be derived from these tags, including impacts of various fisheries.
Even though mark-selective fisheries have been described as “the most intensively sampled fisheries on the Pacific coast,” that effort is not enough.
From the report:
Catch and escapement sampling in some areas is still inadequate for providing the data required for analysis of MSF impacts. This inadequate data and lack of analyses, combined with the large tagging and sampling costs of (Double Index Tag) programs, has led certain agencies to abandon DIT programs (with several more under consideration for termination). Since there is no viable alternative to DIT programs for estimating fishery impacts of MSFs on natural-origin stocks independently of assumption-based methods and models, this trend is alarming.
Double index tags are a method of inserting a coded-wire tag into a fish, but then not clipping the adipose fin. These fish would theoretically be able to escape mark-selective fisheries, adding to the data of their impacts. But because mark-selective fisheries aren’t being monitored enough, double index tagging is being abandoned.
As a result, fisheries managers’ confidence about the impacts of mark-selective fisheries can vary widely from year to year.
The chart below shows how far off pre-season estimates can be. In at least one year, the pre-season models were off by more than 50 percent.
In the end, the report doesn’t call for ending mark-selective fisheries, but rather improving how they’re monitored, sampled and modeled:
Mark-selective fisheries have been prosecuted without consideration to limitations of catch sampling programs or the technical feasibility of evaluating impacts. Complex regulations (e.g., mixed-bag retention restrictions or fisheries at fine spatial or temporal scales) are being promulgated without regard to the need for, or capability to collect, the data required for stock and fishery assessments or to evaluate MSFs. Sampling designs must correspond to the same spatial and temporal strata described by the regulations for the fishery to improve the accuracy of expansions for catch and CWT recoveries. Agencies proposing MSFs need to coordinate sampling programs with the development of analytical tools to measure the impacts of these fisheries.
The report’s executive summary puts forward a fairly long list of observations and complications with how mark selective fisheries and the coastwide fisheries management regime work:
- No viable alternative to the adipose fin clip has been identified as a permanent visual mark for mass marked anadromous salmon. From Selection of a Mass Mark.
- Mark-selective fisheries complicate implementation of PSC fishing regimes. From Significance of MSFs to Implementation of PST Agreements.
- Mark-selective fisheries can significantly change the magnitude, distribution, and uncertainty of fishery mortalities for unmarked fish (usually natural-origin). From Harvest Sharing Agreements.
- Estimation of the fishery mark rate (the proportion of encounters that are marked by time-fishery strata) is critical to harvest management involving MSFs. If mark rates are overestimated, impacts of MSFs on unmarked fish will be underestimated; conversely, if mark rates are underestimated, mortalities of unmarked fish will be overestimated. From Planning Tools and Harvest Sharing Agreements.
- Mark-selective fisheries require a coordinated and consistent approach to implementation of MM, MSFs, and coastwide sampling to enable accurate assessment and management of impacts to natural-origin fish. Adequate tagging and unbiased sampling programs in fisheries and escapement are required for analysts to detect potential differences between mortalities of marked and unmarked fish due to encounter rates in MSFs. Fishery sampling programs have been developed to provide data required to reliable estimates of stock-specific mortality of unmarked fish in individual MSFs, however they have not been implemented coastwide. Alignment of sampling with MSF spatial and temporal strata is required, to facilitate standard reporting of estimations of mortality for marked and unmarked fish. From Development of MSFs and Coastwide Coordination of CWT Sampling Programs.
- Electronic sampling has not been employed coastwide, although it is required to recover DITs in MSFs. Cost, accuracy, practical feasibility, and policy concerns are some of the challenges faced by agencies in incorporating this technology into sampling programs. From Coastwide Coordination of CWT Sampling Programs.
- Mass marking combined with visual sampling increases the cost of CWT recovery, by increasing sampling effort, and costs for storage, transport and tag removal. From Sampling for DITs.
- The increased costs associated with handling and sampling large numbers of marked and unmarked fish has resulted in reduced rates of sampling at some facilities and in fisheries because of agency budgetary constraints. From Coastwide Coordination of CWT Sampling Programs and Costs.
- Visual sampling may adversely affect relations with salmon processors and First Nations, because it requires the removal of a large number of snouts or heads. From Sampling for DITs.
- Improved coordination of harvest management regulations and sampling programs is needed. The SFEC has been unable to develop methods for estimation of MSF impacts on unmarked fish by stock and age under the promulgated regulations. From Regulation of MSFs and Planning and Assessment of MSFs and Coastwide Coordination of CWT Sampling Programs.
- Dissimilar regulations for adjacent areas having slight variations in species, gear, size and bag limit restrictions have complicated compliance, enforcement, and impact assessments. Similar regulations across spatial and temporal strata may reduce angler confusion and enforcement and assessment burdens. Based on reductions in retention of unmarked catch since the inception of MSFs, it is evident that angler behaviour has been modified to harvest selectively for marked fish. From Regulation of MSFs.
- Existing rates for release mortality, mark retention, and mark recognition errors are derived from studies that have indicated substantial variability by gear, vessel type, location, species, and size of fish encountered. Nonetheless, methods and models employed for stock and fishery assessments assume these rates are known with certainty. From Planning Tools.
- A bilateral model does not exist for pre-season planning or post-season evaluation of MSFs for Chinook. From Chinook and Development of MSFs.
- Fishery planning and post-season assessments for MSFs rely upon assumption-based methods that do not account for uncertainty. From Planning and Assessment of MSFs.
- Agencies currently rely on Fisheries Regulation Assessment Model (FRAM) estimates of coho MU-specific exploitation rates for both pre-season projections and post-season mortality estimates. Managers have not accounted for uncertainty in estimating mortalities of unmarked fish in MSFs, instead accepting point estimates produced by the coho FRAM. The uncertainty of projections of mark rates and hence stock specific mortalities from MSFs by the coho FRAM can vary widely from year to year due to the uncertainty of abundance forecasts, variations in migration patterns, and conduct of fisheries. From Planning Tools.
- The SFEC has been unable to develop methods to estimate stock-age-fishery impacts of individual MSFs when multiple MSFs impact CWT release groups. From Planning and Assessment of MSFs.
- Double index tagging programs have not been implemented as recommended. Agencies may not believe that the information provided by the DIT programs justifies their cost. In some instances, cumulative impacts of MSFs have not been large enough to reliably estimate differences in return rates of marked and unmarked fish using DIT programs. From Regulation of MSFs and Double Index Tagging (DIT) and Planning and Assessment of MSFs.
- Uncertainty of fishing impacts on unmarked fish not represented by a DIT group has reduced the ability to estimate impacts of MSFs on unmarked fish. From Double Index Tagging (DIT).
- Coordination among those who set fishery regulations, design the sampling protocols, use the data in models and design data warehouses is critical. From Regulation of MSFs and Coastwide Coordination of CWT Sampling Programs.
- Improvements in reporting and access to information about MSF regulations and impacts on unmarked fish are needed. A prototype for electronic reporting of MSFs has been jointly developed by WDFW and NWIFC for recreational Chinook marine MSFs in Puget Sound and Washington coastal waters. From Coastwide Coordination of Reporting.
- The Pacific States Marine Fisheries Commission (PSMFC) Regional Mark Information System (RMIS) has been modified to accommodate reporting of data for MM releases and CWT recoveries from MSFs. Data standards have been developed by the PSC Data Standards working group and implemented by the Regional Mark Processing Center (RMPC) in the RMIS. From Coastwide Coordination of Reporting.
- Agencies are providing complete MM proposals for the SFEC review by the November 1 deadline. Mass marking levels have stabilized for Chinook and coho production in Washington and Oregon. From Review of MM and MSF Proposals by the SFEC.
- MSF proposals are of limited value in assessing potential impacts on the viability of the CWT program because domestic fishery planning processes have not been completed, so details regarding the location, magnitude, and regulations are often unavailable for review by the SFEC and the PSC. From Review of MM and MSF Proposals by the SFEC.
- Post-season reporting of MSFs remains problematic. In 2013 catch year, 3 post-season reports were received out of 16 coho MSFs implemented coastwide, and 4 post-season reports out of 26 Chinook MSFs were received. SFEC continues to recommend improving compliance with post-season reporting (SFEC 2015). From Post-Season Reporting of MSFs.