FREDERICTON, N.B. – Daniel Boisclair, calm, alert, and with a subtle French accent, took the floor promptly at 9am to open the second day of talks at the Aquatic Reserve Networks meeting.

Like most of us at the workshop, his research at the intersection of mathematics and biology had to do with fish. As he put it, the biological questions are simple: “How many fish are there? Where are they? What are they doing?”

But when it comes to understanding the policy implications, things quickly get more complicated.

Professor Boisclair, in particular, wants to know what happens to river-dwelling fish that share their foraging and breeding habitat with other human uses, like hydroelectric power.

Canada, his home country, currently gets 60% of its electricity from 500 hydropower facilities installed across its broad Northern expanse. This renewable energy source is a terrific boon for people concerned with greenhouse gas emissions, as well as those who want to avoid further exploitation of limited and dirty fossil fuel supplies. But each new set of dams and turbines adds an additional obstacle for migratory fish stocks, many of whose numbers are already depleted by fishing and other forms of habitat loss, like pollution, or diversion for irrigation and other water use.

One way to compensate for the competing interests between fisheries and conservation, and energy and water, is to use temporally variable management. For example, power plants can shut down some of their turbines during spawning runs to allow safe passage of adult fish.

Seasonal management strategies aren’t new to fishery management, though typically they focus on the time of the year when recreational and commercial fishermen can legally harvest a species. (For example, the California recreational Dungeness crabbing season just opened this weekend.)

Limiting the fishing season of a particular species helps to conserve it in several ways. First, it cuts down on the amount of fishing effort that the species is exposed to, meaning that an individual fish has a reduced chance of being hooked and eaten. Second, seasons are typically timed to protect a species at its most vulnerable time of the year. For example, ideally you’d want to hold off on harvesting fish until after they’d completed that year’s spawning cycle, to maximize the number of new offspring that would make it into the next year’s breeding pool.

Perhaps most importantly, though, setting fishing seasons helps regulators walk a fine and enforceable line between the needs of the fish stocks they try to manage sustainably, and the economic and social politics of the communities that have harvested these fish for years, if not generations. Fishing seasons allow some harvest to occur – sustaining at least a portion of the economic base of the industry, but theoretically prevent the overfishing – and eventual collapse – of the species.

Of course, restricting someone’s access to his or her livelihood or favorite weekend activity is hardly going to make you good friends. While hunters and fishermen are often among the most vocal advocates for regulations (Of course they don’t want to see the game they love driven to the brink of extinction!), sometimes the strict management required can be a tough pill to swallow.

The social side of the dynamic becomes much more complicated once multiple regulatory agencies become involved. For example, many fish stocks span international boundaries, which means that several governments must agree on a common policy goal and, more importantly, its implementation.

The difficulty of achieving such international accord was highlighted last week, when the United States and New Zealand tried to establish a half-million square mile marine reserve off the coast of Antarctica. The reserve would have been the largest in the world, creating a safe haven for many marine species that call the Southern Ocean home, including several species of whales and penguins, the charismatic heroes of many a children’s story.

But the reserve would be closed to fishing. So China, Russia, and the Ukraine balked at its establishment, and the conservation effort fell short.

The Antarctic negotiation represents a single example in an ongoing series that will only become more complicated as our demands on the planet’s natural resources increase and diversify. Even as we get better at monitoring and stabilizing our fishery stocks, we’ll subject them to additional pressures from offshore drilling, cross-river hydroelectric plants, and habitats shifted by ocean acidification and sea level rise.

And there will hardly be enough time in a year to manage it all.

Didn’t buy the story hook, line, and sinker? Holly welcomes reader feedback at hollyvm “at” stanford.edu.