(c) Jim Patterson Photography, https://jimpattersonphotography.com/
By: Rod Fujita & Kendra Karr
Fisheries management is principally focused on managing fishing pressure, with the goal of keeping individual fish stocks healthy enough to produce good yields. But fisheries also affect the basic processes that keep ocean ecosystems healthy. This is why it is important to understand how many fish need to be in the system to maintain the many important services that an ocean ecosystem can produce — including the maintenance of biodiversity, tourism value, and fisheries — and to manage fisheries so that fish populations remain at about that level.
The evidence that fish are important regulators of ecosystem processes is particularly strong in coral reefs. The abundance and variety of fish is one of the most striking aspects of a healthy coral reef. Some species transport energy and nutrients between seagrass meadows and the reefs. Grazing fish species on a healthy coral reef keep seaweeds that would otherwise over-grow the reef in check. Predators regulate populations of prey species, responding to natural variability by adjusting their feeding rates and numbers. On a healthy reef, many different species occupy each of these niches, and each does their job in a slightly different way. This enables the reef to resist threats and other changes (like hurricanes) and to recover from very storms or human impacts, within limits of course. Read More »
Recently, the impacts of climate change on fisheries have been in the news. The emphasis has been on the inability of scientists to explain how climate change is affecting fisheries or to fix the problems it seems to be causing. These include shifting distribution and abundance patterns of commercially valuable fish stocks – shifts that may leave fishermen stranded with very restrictive catch limits, even when they have been doing everything possible to protect and restore their stocks. These problems are being felt acutely in New England, where catch of some valuable stocks has been highly restricted to rebuild stocks depleted by overfishing – but they face even more restrictions as scientists find less fish in the water, possibly due to migrations induced by climate change.
A better scientific understanding of how climate change influences the distribution and abundance of fish is certainly needed, but that may be less important than the need for more flexible human institutions that can rapidly adjust to those changes. Read More »
Ocean conservationists have been arguing for a long time that marine reserves are a good investment, because they help sustain many ecosystem services, including fisheries and tourism. Various studies have helped to quantify the value generated by marine reserves, but a new study puts it all together and presents a convincing value proposition for marine reserves. Now all we need are investors who can appreciate that value proposition and make it work economically, and the right combination of rules and governance that will make these new kinds of markets – ecomarkets – viable.
The benefits of marine reserves often outweigh the costs of establishing and maintaining them. You would think that there would be great demand for them, but instead the pace of marine reserve establishment has been slow and conflict-ridden. Why? Because many groups of people benefit from the status quo, and would suffer short-term economic harm from marine reserves. Also, the benefits of marine reserves take several years to accrue, while the costs are immediate. And while some of the benefits are fairly concrete and flow to discrete user groups – like lower fishing costs and higher fishery yields near the borders – others are less concrete (e.g., biodiversity and aesthetics) and flow to many user groups (e.g. tourists and people who like natural environments), including some (e.g., future generations) that don’t have much say in present day decisions.
So theoretically, marine reserves can pay for themselves and then some. But right now, few people want to invest in them. How do we change that? Read More »
To paraphrase F. Scott Fitzgerald, the test of a first rate intelligence is the ability to entertain two opposed ideas at the same time and still function.
Two views on the importance of catch data for estimating the abundance of fish populations are portrayed as opposing ideas in recent articles, but both of the “antagonists” display first rate intelligence by coming to the same conclusion: catch data send an important signal about the status of a fish population, but other kinds of information must be applied to avoid being confounded by all the other things that affect catch and come to a reasonably accurate estimate of fish abundance.
This argument over methodology may seem arcane, but the stakes are high: estimates of the status of global fisheries based on catch data, which are available for most fisheries, suggest they are in pretty poor shape, because catches have declined sharply in many of them. But when one looks at stocks that have been assessed by scientists who take into account fishery-independent measures of abundance, the situation looks far less dire, because decreases in catch can result not only from decreased abundance, but also from changes in markets, environmental conditions, regulations, and even in what fish are called – Hilborn and Branch point out that in the 50’s, all sharks were put into only 7 categories, but now there are 36 groups for which catch data are collected, so that reduced catch in some of the earlier categories may merely be the result of re-classification. Read More »
Social change requires the harnessing of social forces, and the more powerful the force, the more fundamental the change. Moral outrage, a yearning for justice, and the desire for connection are all forces that have propelled social change movements throughout history. They will continue to fuel social change now and in the future.
But there is a very powerful force shaping the world we live in today that is not yet aligned fully with the environmental values that many of us hold, and that is the search for profit and well being through the investment of capital and labor — the profit motive. Indeed, the profit motive has prevailed time and again over countervailing forces like ethical commitments to environmental stewardship, the desire for long-term economic well being, and even over the force of government regulation.
In a previous blogpost, I summarized a recent publication that lays out a strategy for aligning the profit motive with the conservation of coastal ecosystem services like carbon sequestration, storm surge protection, and recreational value — services that are usually unpriced by conventional markets, and so become subject to degradation. The goal is to reverse alarming trends in mangrove deforestation, salt marsh dredging, and nearshore pollution by shaping markets that value these services, allowing people to do well by doing good. Read More »
Good science should always guide policy. In the ocean, policy reflects decades of scientific work on single species and on single endpoints, like water quality. However, it is now clear that ocean ecosystems are more than the sum of their parts, and policy needs to catch up to this new scientific understanding.
Of course, we must continue to protect the aspects of ocean ecosystems that we value the most. Fisheries need catch limits to keep stocks at sustainable levels. Pollutants need caps to keep waters fishable and swimmable. Forestry and farming need best practices and standards to keep estuaries healthy. But it turns out that ocean ecosystems have tipping points – ecological thresholds beyond which they undergo dramatic changes.
Healthy and resilient ocean ecosystems function similar to the United States government’s system of checks and balances—different species do similar things but in slightly different ways, which help keep these systems both interconnected and even-keeled. However, when we reduce species populations so much they can no longer do their part, we alter the natural balance of the system, which can have grave effects.
Luxuriant kelp forests that support marine mammals and a myriad of other species provide us with various ecosystem services like seafood, agar (sugar made from kelp), recreation, and sheltering the coastline from waves. However, these habitats can turn to rocky barrens very rapidly when they reach their tipping points. We witnessed this in the 1800s when fur hunting became prevalent—decreasing the sea otter population. With fewer sea otter to consume urchins, urchins became overabundant, overgrazing the kelp and causing forests to disappear.
Fortunately, science is providing insights into the factors that make ocean ecosystems more capable of resisting these kinds of changes, and more able to bounce back when they are damaged; in other words, the attributes that make some systems more resilient than others. Having lots of species with different ecological jobs (biodiversity and niches) is very important, as is having several species doing the same job but in slightly different ways (functional redundancy). Lots of genetic diversity within species and populations is important as well. It's a little like rocket science: rockets are complex systems that are made more robust and resilient (i.e., less likely to blow up) by building in redundant subsystems. Nature has done that one better by building in even more diversity, allowing coral reefs for example to recover from hurricanes and even volcanic eruptions that devastate human communities.
In an ocean in which the temperature, pH, currents, weather, and human uses are changing, it makes much more sense to manage for resilient ecosystems than manage for maximum sustainable yield of one species or another. Who knows what the next big impact to the ocean will be? We need to increase resiliency so that no matter what, ocean ecosystems can persist and continue to provide the many valuable ecosystem services upon which we depend. Our new paper draws on the science of ecosystem resilience and lays out a policy framework for achieving this goal.