Criteria for a good catch: A conceptual framework to guide sourcing of sustainable salmon fisheries

The recent diversity and distribution of wild Pacific salmon derives from complex, dynamic freshwater and marine environments that have shaped populations through multiple generations, following the end of the Pleistocene glaciation, approximately 10 000 years ago (Waples et al. 2008). New freshwater spawning and rearing environments, estuaries, and ocean habitats offered numerous ecological niches that salmon recolonized, adapted to, and exploited. As described by Stanford et al. (2005), the dynamism of river/floodplain/estuary systems results in a temporally and spatially shifting mosaic of rearing and spawning habitats that drives the local adaptation and life-history diversity of wild salmon. This process has maintained (1) a balance between egg fecundity (several thousand per female) and large egg size that ensures survival to emergence in freshwater, subsequent juvenile survival to ocean entry, and then adequate returns as adults to replace the parental generation (Fleming and Gross 1990; Einum et al. 2002; Heath et al. 2003) and (2) high homing fidelity of returning adult spawners to natal habitats in freshwater (Hendry et al. 2004; Quinn 2005). Local or place-based adaptation has been defined as a “process that increases the frequency of traits within a population that enhance survival or reproductive success of individuals expressing such traits” (Taylor 1991, p. 185). Thus, these adaptations involve suites of biological and behavioral characteristics that are under varying degrees of genetic and epigenetic control (Hutchings 2011; Salvolainen et al. 2013). Biological characteristics that drive and reflect local adaptation include:

This suite of life-history characteristics has evolved to provide a solution to the challenges that salmon face in finding favorable and productive habitat during each life cycle stage in sequence, temporally and spatially, from spawning grounds to freshwater rearing to ocean migration and adult return to natal watersheds. This process results in salmon populations possessing a portfolio of successful life histories organized at a hierarchy of spatial scales that serve to buffer local and metapopulation complexes from environmental variations that can affect survival at different life-history stages (Schindler et al. 2003, 2010; Moore et al. 2010, 2014; Satterthwaite and Carlson 2015). Moreover, salmon populations fulfill key ecological roles (niches) within the salmon ecosystem throughout their life cycles, as detailed below.

Salmon also experience high levels of intraspecific competition for finite amounts of rearing space and food. As such, they have evolved a suite of juvenile growth strategies that enable populations to thrive in spite of intense competition for food and cover, predators, and widely varying environmental conditions such as temperature and salinity (Groot and Margolis 1991; Quinn 2005; Moore et al. 2014).

Salmon reproduction is characterized by moderate levels of fecundity (egg numbers of 2–12 000) and large egg sizes relative to most marine fishes (4–8 mm diameter, Groot and Margolis 1991; Quinn 2005). Egg size is adapted to provide for relatively high embryo survival and subsequent fry dispersal to rearing habitats. A population’s mean egg size and number is the likely result of adaptation to the range of average environmental conditions that affect juvenile growth and survival, marine survival, and ultimately productivity (Fleming and Gross 1990; Einum et al. 2002; Braun et al. 2013).

Complementing these characteristics of salmon fecundity is the presence of multiple ages of maturity, with the notable exception of pink salmon that mature at a single age (two). Multiple ages of maturity result in overlapping generations (Waples et al. 2013) that further buffer environmental variation and contribute to the portfolio of different life histories (Moore et al. 2014; Copeland et al. 2017). This helps to explain the persistence of wild salmon presence across much of the northern hemisphere and their rapid dispersion after introduction to non-native habitats of Chile, Argentina, and New Zealand (Quinn et al. 2001a, 2001b; Quinn 2005).

Lichatowich and Williams (2009, p. 1011) characterized a conceptual foundation for fisheries management as “the set of principles, assumptions, and beliefs about how ecosystem processes influence or control fish productivity. A robust conceptual foundation therefore determines what problems (e.g., limitations on production) are identified, what information is collected, and how it is interpreted, and as a result, establishes the range of appropriate solutions”. It also determines broadly where the “burden of proof” lies when developing fishery management plans (Dayton 1998; Gerrodette et al. 2002; Charles 2002). Burden of proof in this context would identify where harm from a contemplated action is presumed to result and which party—the party proposing the action or the party opposing it—must demonstrate that the potential harm is, or is not, likely to occur. Under the place-based conceptual foundation, the burden lies on those proposing a specific fishery management action to demonstrate (with sufficiently high probability) that the action assures spawner escapement goals will be met and associated ecosystem services provided by the exploited population(s) will not be impaired.

Thus, we grounded our sourcing criteria within a scientific and philosophical framework that emphasizes place-based life-history diversity within and between the five species of wild Pacific salmon native to the north eastern Pacific Ocean (sensu Lichatowich 2013; see also, Lichatowich et al. 2017) and in a burden of proof context. As described in the Ecosystem section, diversity of Pacific salmon manifests at the population level from unique adaptations to specific conditions within freshwater habitats and the high degree of homing fidelity to these natal sites. This fundamental character of wild salmon—and the conservation and management considerations that emerge from it—are referred to as place-based. Most contemporary management schemes mix or amalgamate populations, even within river systems and thus to varying degrees depart from this basic tenet and obfuscate assessment of sustainability. We use the term “population” instead of the more common term “stock” to emphasize our focus on the place-based character of wild salmon (see also, Waples and Gaggiotti 2006).

The aspects of salmon ecology that we argue are associated with high intraspecific competitive abilities in juvenile rearing habitats (including a modest number of relatively large eggs, multiple ages at maturity, and the resulting overlapping of generations) have significant implications for salmon harvest management. Salmon populations are composed of portfolios of life histories that are organized at hierarchical spatial scales, primarily within and between river basins. Each population within a portfolio is place-based, a product of the selective forces operating within the range of habitats to which the population and its component life histories have adapted.

Because the individual population is the fundamental unit, population portfolios within river basins are likely to be particularly important for the resilience of the larger river basin portfolio (Moore et al. 2010, 2014; Carlson and Satterwaite 2011). These populations at the “within-river basin” scale are most vulnerable to exploitation because they are numerically smaller than populations at the aggregate whole-basin or regional scale (e.g., the entire Fraser or Skeena River systems versus the Chilcotin or Babine Rivers that are a tributary to the main Fraser and Skeena Rivers, respectively). Salmon harvest (and salmon population management more generally) must, therefore, emphasize the preservation of the adaptive integrity of individual populations within river basins. And, importantly, this requires managing salmon harvest to assure that spawning escapements at a level equal to or greater than maximum sustainable yield (MSY) are consistently attained in the majority of return years for all target populations.

The current framework for US and Canadian harvest management of Pacific salmon is firmly based in the concept of MSY. MSY is defined as the level of average annual spawning escapement (or total egg deposition) that will produce the greatest total recruitment in excess of the average parent spawning escapement under prevailing average environmental conditions affecting recruitment. MSY is estimated from stock-specific data used to estimate adult-to-adult recruitment parameters of a presumed appropriate stock-recruit model. Although there are concerns whether MSY spawning levels are sufficient to preserve locally adapted populations or, more concerning, whether MSY is at all compatible with an ecosystem approach to fisheries management (Larkin 1977; Sainsbury et al. 2000; Mangel et al. 2002; Pikitch et al. 2004; Cadrin and Pastoors 2008), we believe that, if the MSY approach is used, minimum escapement levels for individual populations must be estimated from high-quality time-series data and estimation procedures account for all major sources of uncertainty. Consistent attainment of minimal spawner escapements is necessary to maintain a population’s life history, genetic diversity, and intraspecific competition at levels adequate to drive adaptation to changing environments.

One of the principal sources of uncertainty for assuring that MSY (or greater) spawner escapement goals are consistently attained is the current mixed-stock nature of most marine salmon fisheries. Most wild salmon harvest is managed at broad spatial scales at which multiple populations of target species are encountered. Management of salmon populations as large aggregate stocks is implicitly in conflict with the place-based character of salmon that is fundamental to their long-term viability and resiliency. This further implies that such management is in conflict with the preservation of salmon diversity and life history complexity. To varying degrees, depending on the stock aggregates, such management is placeless and largely exonerates management from the need to maintain specific wild salmon populations.

In Box 1, we list the basic criteria for retail sourcing of salmon from sustainably managed fisheries. The criteria were based on fundamental principles of salmon ecology and developed as a result of our work with the Patagonia Provisions program; these criteria can be applied by any retailer sourcing wild salmon that wants to assure consumers that its salmon products meet a high standard for sustainability. The criteria attempt to capture the primary features of place-based salmon ecology as they apply to the acquisition of salmon products from fisheries that meet or closely approach the place-based ideal. We discuss the strengths and weaknesses of the criteria after listing them.

These criteria represent a foundation for the support of place-based salmon management by conscientious retailers who desire salmon products from sustainable fisheries. The criteria embody two key elements of place-based fisheries management. First, they allow selection of populations currently managed for MSY if accompanied by clear evidence of regularly attaining or exceeding those MSY-determined escapements. Second, other criteria emphasize fishing practices that demonstrably sustain target populations without adverse effects to their respective ecosystems. This requires chain of custody documentation on the product label delivered to consumers. This requirement differs from consumer advisory services such as SFW that do not address chain of custody and from assessment bodies employing third-party assessors, such as the MSC. MSC only requires traceability of a certification unit to a supplier and doesn’t provide fishery details on the label. This addresses the difficulty most establishments selling sustainable seafood currently experience—they cannot answer consumer questions about which population or fishery the salmon they sell comes from or what gear type was used to catch it. Adherence to the criteria in Box 1 ensures a high-quality, sustainable salmon product that supports value-added processing and a high return to fishers and their communities.

A related feature of our criteria is the absence of conditional approval for a product caught in a fishery that does not fully meet the criteria. Salmon from an MSC fishery that have been certified “sustainable” but with “conditions” are indistinguishable at the point of sale from salmon from a fishery certified unconditionally. Consumers have no knowledge that the fishery has failed one or more sustainability criteria or received conditional certification and repeatedly failed to meet the conditions (see Christian et al. 2013). Acceptance of a product under our approach is all or nothing: a product is accepted if and only if it meets the criteria.

As a policy, Patagonia Provisions has chosen not source hatchery-produced salmon. Sustainable, place-based salmon management requires an approach that is not reliant on, or attracted to, technological subsidies to harvest from large-scale hatchery production that imposes high ecological costs on wild salmon and undetermined economic costs on society (NRC 1996; Knapp et al. 2007; Radke and Carter 2009; Lichatowich et al. 2017). Place-based management also requires the employment of selective fishing practices and gears that enable non-target salmon populations to be released with a high probability of post-release survival to spawn. Place-based management also supports a focus on the preservation and restoration of natural physical processes that form and maintain salmon spawning and rearing habitats (sensu Stanford et al. 2005). The criteria we have developed for sourcing salmon support these objectives.

We believe that place-based salmon management is most likely to succeed when most, perhaps all, salmon harvest occurs at spatial scales closer to the rivers of origin than today’s mixed-stock marine fisheries, much as it did in the early 20th century (Lichatowich 2013; Price et al. 2013). Data requirements for place-based management are likely to be relatively high in the short term because of neglect on the part of management agencies to prioritize or fund regular monitoring of smaller spawning populations often caught in mixed-stock fisheries (Price et al. 2008, 2017; Lichatowich et al. 2017). There is a need to identify the diversity of component stocks in large terminal river systems, monitor the abundance and productivity of component populations, determine sustainable spawning escapement reference points (levels > = MSY), and determine effective harvest control rules through precautionary management strategy evaluations (e.g., Pestal et al. 2011).

In the long term, after stock-specific baseline data have been collected, data collection and analysis are likely no more costly than appropriately risk-averse management of aggregate populations in mixed-stock fisheries, and are certainly more compatible with the place-based character of salmon populations. For example, at regional levels (e.g., the Skeena River, the West Coast of Vancouver Island, northern Puget Sound, Washington (Oregon) tributaries to the Columbia River downstream of the Bonneville Dam) rotating panels of sites in selected river systems can be identified to systematically monitor component populations representative of the sizes and life histories of regional populations. Sampling can be conducted at appropriate frequencies (e.g., annually, once every three to five years) to acquire the requisite data for estimating escapement and harvest rates for individual populations. Once these sustainable escapement levels have been identified, the relationship among physical habitat characteristics (such as basin or floodplain area, e.g., Parken et al. 2006; Liermann et al. 2010), equilibrium abundance, and sustainable escapement levels can be robustly estimated and the results applied to unsurveyed populations with greater confidence than at present. Although robust cost estimates are needed, we expect that the costs of the data acquisition and monitoring necessary to support place-based MSY-plus management at the regional level will be no greater than that required to manage current mixed-stock marine salmon fisheries. Regardless, the costs of monitoring necessary to assure that wild populations are being sustainably managed should be borne by the fisheries as they are a component of the necessary management costs of the fisheries. Failure to undertake and fund such monitoring, thereby internalizing these management costs, treats the costs imposed on wild populations in the form of overfishing, under-escapement, population declines and (or) future lost fishing opportunities as externalities subsidized by the public, both present and future generations. Sustainability requires that such subsidies be eliminated (Lichatowich et al. 2017).

We do, however, acknowledge that it is possible, in principle, to manage aggregate stocks in a manner that accounts for the presence of component populations and to be consistent with place-based management. Such harvest requires a costly research-based adaptive management infrastructure that includes extensive sampling to acquire high-quality genetic stock identification data and a robust array of frequent spawner escapement estimates. These data would provide the information required to determine the impacts on all salmon populations encountered by a mixed-stock fishery and to follow those effects to the spawning grounds with sufficient detail and sampling frequency to determine with high confidence that population-specific sustainable escapement targets are being attained. Considerable progress has been made on the first component (development of genetic stock identification (GSI ) databases for most mixed-stock fishery aggregates on the US/Canada west coast, reviewed by Seeb et al. 2007 and Moran et al. 2013, Hess et al. 2014), but the resolution remains at the scale of large basin aggregates not individual component populations (though see Steele et al. 2013 for recent progress on stock-specific GSI and parentage-based tagging in the Columbia Basin). Until these elements are in place, mixed-stock marine salmon fisheries will fall short of the required sustainability standards (assuring and verifying regular attainment of MSY-based or greater spawner escapement and accounting for all by-catch and incidental mortality to assure that non-target salmon populations are not over-fished). A lower cost interim remedy for these fisheries would be the adoption of a robust MSY-plus management regime under which current MSY estimates are treated as limit thresholds.

Transitioning all, or a majority of, salmon management to the place-based approach will be challenging and will not occur overnight. Management of salmon harvest with selective gears and at more local scales than the mixed stock fisheries currently operate will, in the short term, not benefit everyone in commercial fishing communities. Some individuals will not be able to continue fishing with their current gears and may not be able to transition to selective practices and more terminal fisheries. In addition, overall harvest levels will likely have to be reduced. As well, many of the large-scale hatchery programs that currently subsidize unsustainable harvest levels with high ecological effects on depressed and at-risk wild populations (including adverse genetic effects from straying of hatchery fish to wild spawning grounds (HSRG 2009, 2015)) will have to be reduced in scale if not eliminated altogether. But these transition costs can be addressed, especially if planned for as part of a comprehensive reconfiguration of regional salmon fisheries. The criteria we have developed recognize the complexities of this transition and take into account the current state of salmon fisheries that complicate the ability to identify sustainable fishing practices. For example, the criteria require that candidate salmon sources frequently attain MSY-based escapement goals supported by well-documented evidence. Within fisheries that attain this escapement threshold, the criteria prioritize selective fishing gears that are passive (traps, reef nets) or close to passive (set gillnets) and then prioritize fisheries that land fish promptly while still alive and bleed and ice them soon after landing. There are few salmon fisheries that meet these criteria and have products available to conscientious retailers. The desire for such products should move salmon managers toward place-based management. Indeed, we endeavored to build a modicum of flexibility into the criteria to support salmon fisheries and products that strive to be consistent with the place-based philosophy at the beginning of this transition.

The short- and long-term benefit of such a transition is great. Place-based management with selective practices and gears will result in higher quality products due to more careful handling of individual fish. This will generate a premium sustainable product that provides a higher price to fishers per fish landed. Of equal importance, place-based, selective fishing practices, and gears such as salmon pound nets (traps), fish wheels, and reef nets, have a significantly lower carbon footprint than purse seine and gill net vessels operating in large rivers, estuaries, and the coastal nearshore. Consequently, fuel and related travel costs are much lower. Combined with management for larger and more consistently attained spawning escapement goals, place-based fisheries will have a higher probability of fishing opportunities on stronger wild salmon stocks than current mixed-stock fisheries. These features of place-based management and fisheries will reinvigorate local fishing economies and communities with resulting social benefits that are likely to be non-trivial.