Step 1: Goal Setting
If you don’t know where you are going, any path will get you there. Be careful of what you wish for. The trouble with not having a goal is that you can spend your life running up and down the field and never score.
There are lots of sayings about goals, because it’s so important to get them right. Fisheries management is no different – having clear goals is essential, because they should guide every decision.
It may seem obvious what the goals of fisheries management are – sustainable yields, stable jobs, and ecosystem health are often cited. Fisheries often have multiple objectives, and achieving them requires varying amounts of fishing mortality and stock abundance (how many fish are in the water) (Figure 1).
For example, one objective might be maximizing the amount of landings (or yield) that the fishery can sustainably produce over many years. This is known as Maximum Sustainable Yield, or MSY. MSY is difficult to calculate, but as a very approximate rule of thumb, it is often associated with stock abundance levels that are approximately half of the abundance levels that would exist if no fishing took place at all. This will depend strongly on the life history (e.g., growth rate and productivity) of individual species. So if you think your target species fit these rules of thumb, achieving MSY would require fishing the stock down to about half of it’s natural abundance (i.e., the number of fish present before fishing started, or the density of fish in a mature, well enforced no-take reserve), and then maintaining fishing mortality so that abundance stays at about that level, leaving the other half to sustain the stock. MSY can be associated with relatively high levels of fishing mortality if the stock is fairly abundant.
However, if another objective of fishery management is to maximize profits, it may be necessary to reduce catch in order to allow the stock abundance to increase to higher productivity in the future. Fishing costs tend to go down when abundance goes up as the fish are easier to catch. If the fishery includes recreational fishing businesses that value high encounter rates and big fish, fishing mortality may have to be reduced even more because recreational fishermen are likely to get more bites and catch more and larger fish when stock abundance is higher.
Protecting the ecosystems that support fisheries should always be an important objective of fishery management. This means leaving enough fish in the water (i.e., adjusting fishing mortality) so that the fish can fulfill their ecological roles such as preying on other species, serving as food for predators and moving energy and nutrients through the ecosystem. We list several common fishery objectives in Table 1.
Figure 1. Different fishery management goals often require different levels of stock abundance, called biomass. Bmsy = the biomass associated with generating maximum sustainable yield. Bmey = the biomass associated with producing maximum economic yield. Beco = the biomass associated with allowing fish to fulfill their ecological roles. Brec = the biomass associated with achieving recreational fishery goals of high encounter rates and large fish. This figure is for illustrative purposes only.
Table 1. List of common fishery management objectives and considerations.
|Biological/ Ecological Objectives||Economic Objectives||Social/ Cultural Objectives|
|Protect spawning stock biomass||Increase, fishing profits||Increase or maintain local fishing jobs|
|Limit fishery truncation of age structure||Increase price per fish||Increase fishing safety|
|Protect essential behaviors||Increase production||Protect cultural fishing traditions|
|Protect essential habitat||Decrease fishing costs||Increase or develop community involvement in management|
|Decrease bycatch||Increase product quality||Decrease conflict|
|Improve ecosystem health, resilience, and biodiversity||Increase fishing/ supply chain efficiency||Improve community livelihoods and wellbeing|
Goal setting should always be a stakeholder driven, inclusive process. Together, stakeholders should consider all possible desired goals for the fishery, both long- and short-term goals, and then narrow them down to a list of goals that can be addressed with fishery capacity and resources. Trade-offs between goals should be acknowledged and addressed – when there are trade-offs (e.g., between increasing fishery profits and decreasing fishing mortality to protect or restore a vulnerable stock) stakeholders must either determine which goal they value more highly, or develop a compromise goal that does not result in tradeoffs (e.g., increase fishery profits by increasing demand for more resilient stocks that can be harvested without negative impacts on vulnerable stocks). The Downloadable Workbook includes a brief worksheet that can help stakeholders define goals.
Goal Setting in a Multi-Species Fishery
When working in a multispecies fishery, where multiple species are simultaneously captured by the same gears, there is another factor that must be considered during the goal setting process – the risk of serial depletion. Serial depletion refers to the depletion of individual stocks within a multispecies fishery, one after another. Typically, large, tasty fish that are easy to catch are depleted first. Then smaller, more cryptic fish are depleted. Finally, small pelagic fish and invertebrates are fished down. This can happen when species that differ in their productivity and susceptibility to fishing are fished at the same rate. Species with lower productivity and higher susceptibility like grouper that aggregate to spawn will be depleted first. Species with high productivity that are more difficult to deplete like sardines or lobsters are more resilient and can persist even when fishing effort is high. Serial depletion can happen even as total catch remains high, masking the depletion of individual stocks and setting the fishery up for collapse.
Stocks that are vulnerable to depletion and are caught in multispecies fisheries are called “weak stocks.” The presence of weak stocks in a multispecies fishery makes management complex because protecting these stocks from overfishing often limits fishing opportunities on target stocks, reducing the economic potential of the fishery. Thus, the real challenge in a multispecies fishery is to avoid depleting weak stocks while still maintaining good economic outcomes (jobs, profits, etc.).
Another problem is that species in a multispecies fishery are not only caught together, they also interact with each other in many ways that can have a dramatic effect on management outcomes. This means that trying to manage a single stock while ignoring the others could result in accidental overfishing or a reduction in total system productivity. Furthermore, serial depletion can not only result in fishery collapse, it can also result in ecosystem collapse. All the species in an ecosystem community play important roles and depend on each other to keep the system functioning. Many marine ecosystems exhibit tipping points, at which large changes occur in response to relatively small changes in drivers. Because fish are important regulators of ecosystem structure and function, serial depletion of individual stocks can be an important driver of ecosystem state change.
So in multispecies fisheries goals must not only include the production of good yields from single stocks, they must also include the avoidance of serial depletion and the prevention of adverse impacts of fishing on marine ecosystems.