Portuguese fisheries biologist at the Smithsonian

Dr. Teresa Cerveira Borges is a biology professor at the University of Algarve's Center for Marine Sciences and a member of that institution's interdisciplinary Biopescas research group. She's involved in a number of projects at once, which she outlined for the audience at the March 15 science lecture at the Smithsonian Tropical Research Institute's Tupper Auditorium.

She's studied the area's cephalopods a lot, documented the fishery's biodiversity, conducted educational programs for kids high school aged and younger, and in particular has studied the impact of commercial fishing by looking at the by-catch and discards, fish that are brought up in the various nets but thrown back into the sea for one reason or another.

The world's fisheries are everywhere collapsing or threatened, such that the European Union is very interested in facts that would help them regulate fishing methods and thus preserve the area's fish stocks. But Cerveira noted that there are many differences among Europe's fisheries, encompassing things like the dining preferences of the different nationalities (the Portuguese eat lots of seafood, and prefer to cook fish with the heads on), the ecological impact of dumping by-catch back into the sea (more of a pollution concern in colder northerly waters than off of southern Portugal, so it seems), and the physical and biological impacts of various fishing metiers ("methods" in French and the jargon of fisheries science).

When looking at by-catch, Cerveira is interested in why things get discarded, the biology of the discarded species and the ways they fit into marine environments.

So why the interest in fish with no direct commercial value? There can be many reasons. Those species that come up in the nets and are inedible to humans may be food for fish that people do like to eat. Or they may be predators on organisms that left uncontrolled could throw the whole balance of a marine ecosystem out of whack. Or they may be the sea's analogues of the coal mine canaries, species that are especially sensitive to environmental changes of wider concern.

But not all discards and by-catch are necessarily unfit for human consumption. A lot of times fishing boats with limited refrigeration capacity will haul up a variety of edible species and only the most valuable, or the part of the catch that's freshest, will be kept.

Thus the Biopescas team divided the discarded fish it encountered into three broad categories: 11 species that are occasionally discarded, 70 that are frequently thrown back, and 186 that always get dumped. They cross-indexed these findings according to the metiers of trawls dragged along the sea bottom to catch crustaceans, trawls that are aimed a little higher at catching fish, purse seines and trammel or gill nets.

Trawlers produce the most discards and gill nets the fewest. The reasons for discards are generally different as well, given that fewer inedible species are caught in gill nets but because of the length of time that these nets stay in the water a number of the fish that are caught in them get nibbled on by smaller fish or decompose past the point of commercially marketable freshness before they are hauled aboard the fishing boat.

The data the Professor Cerveira and her colleagues collect form part of the information base upon which national and European officials make regulatory decisions. The regulations address such issues as the minimum size of fish to be kept, the maximum allowable percentage of by-catch, fishing seasons and the size and types of nets that are allowed.

One part Biopescas's work involves the use of a deep sea submersible to examine the sea floor, and video that Cerveira showed of the gouge marks left by bottom-dragging trawl nets used to catch the increasingly rare Norway lobsters in a 300-meter-deep canyon in Portuguese waters. The sea floor looks barren, and archaeologists working with the group have found few artifacts despite centuries of recorded shipwrecks in the area. It appears that the heavy trawl nets break up most of the things in their paths, with the notable exception of a boulder formation that none of the geologists expected to be there, and around which fish life abounds.

(This reporter asked if this discovery says something about the value of deep reefs that might promote the practice of artificial reef-making. Cerveira noted that the value of such underwater structures is well known and that Portugal is a world leader in their production.)

Another project has been the design of new octopus fishing pots. The Portuguese have their traditional devices for this purpose, clay pots with a distinctive shape from those used by their Spanish neighbors. The biggest problem from the fishing point of view is that clay pots are breakable and must be frequently replaced. Then there's a long-running debate about whether octopi can get out of traps and under what circumstances. "As a fisheries biologist," Cerveira noted, "I am very interested in any gear based on the behavior of the animal."

It turns out that Portuguese octopus traps really don't imprison the mollusks against their will, but provide them with places to eat and digest their food with a bit of the privacy they prefer. By experimenting with various materials, the researchers found that octopi like the color black, prefer the amphora shape and don't have any special preference between clay and plastic. Thus the old clay vessels are giving way to more durable plastic ones in Portugal's territorial seas.

Panama has certain fishery regulations, in part based upon that data that our own marine biologists collect. However, Portugal is more advanced than Panama in this field and Cerveira's lecture was thus a special treat for a few fisheries specialists in the audience.

After the lecture an informal discussion ensued about Panama and the state of public consciousness about fisheries issues here. It was noted that in last year's election campaign fishing was hardly discussed, with the exception of a certain amount of criticism of the Moscoso administration for selling fishing licenses to Asian boats. Cerveira, who has not studied Panama's specific conditions, was unsurprised. "People who are doing nothing about a threatened fishery will often start to protest whenever they see a foreign boat," she said.

Earlier, in the audience question-and-answer time, she talked about the problems of fisheries regulation. For example, when governments impose limits on the number of fishing boats, they often at the same time give loans or subsidies to modernize the remaining fishing fleet --- typically by the acquisition of larger, more efficient boats with larger nets and more storage space, which then haul up more marine life than the vessels they replaced.

As a practical political and economic matter, Cerveira opined, "we can not just say to fishermen: 'don't trawl.'" However, she noted that her country's fishing industry now works under new legislation by which the government says exactly that, generally for two months a year.

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