Boom-and-bust eel fishery looking for secure future

Press, 14 January 1986, Page 21

Boom-and-bust eel fishery looking for secure future

The Lake Ellesmere commercial eel fishery has shown the classic profile of a boom and bust industry, according to a management planning report. Since 1978, commercial eel catches have dramatically declined in Lake Ellesmere and the exact cause of this is unknown, says Dr John Town of the Ministry of Agriculture’s fisheries management division, who wrote the report on the commercial freshwater eel fishery.

“It is probably the result of a complex interaction between water quality, lake openings, and overfishing,” he adds. “Lake Ellesmere production lagged behind the national effort and did not yield more than 100 tonnes per annum until 1971.

“Thereafter catches rose rapidly, peaking at 847 tonnes (56 per cent of the national total) in 1976. Eight years later the lake yielded only 89.6 tonnes (6.8 per cent of the national total).” More control over eel fishing in Lake Ellesmere began in 1977 with the issuing of new fishing permits and in 1978 by a controlled eel fishery. This was in response to the open access system that was depleting fishable stock while rising prices encouraged a greater fishing effort.

A Total Allowable Catch (T.A.C.) was introduced with the minimum quota sufficient to provide an adequate economic return and the number of fishermen restricted.

“The long-term management objectives of economic viability and efficiency at minimum economic and social disruption have not been met,” Dr Town says. “If the initial reduction in fishing effort had been

By

TESSA WARD

maintained the prevention of stock depletion may have been achieved.”

In 1982, it was reported that catches had declined, effort had" fluctuated, eel condition had fallen, the mean length of male migrants had dropped, and overfishing was growing. “Some major reasons why the long-term objectives for the controlled fishery had not been met were poaching of eels, the possibility of the T.A.C. being set too high, and insufficient long-term decreases in effort. Anticipated increases in eel growth did not occur, the general environment of the lake deteriorated, and a minimum size limit had not been introduced.”

The management of Lake Ellesmere fishery is complicated by several factors, Dr Town says. “The lake is very highly eutrophic and likely to remain so. “Eutrophication is the nutrient enrichment of waters which can result in the increased production of algae and macrophytes, deterioration of water quality and fisheries, and other symptomatic changes. The major contributors to eutrophication in Lake Ellesmere are phosphate-rich runoff from adjacent agricultural land and high nutrient loads from inputs draining sewage settling ponds.” Poor water quality in Lake Ellesmere has been a cause of concern since 1970. “Extensive weed beds, destroyed by the Wahine storm in 1968, have failed to become re-established. This re-

presents a marked decrease in habitat complexity and available cover.

“During daylight, eels require "cover and population densities are usually directly related to the cover available. Weed bed loss has probably also resulted in a reduction of available weed-associated food organisms.” Lake Ellesmere has no permanent opening to the sea and when the lake level reaches a certain height an opening to the sea is excavated mechanically.

“An outlet to the sea has a number of beneficial effects as it can allow maturing migrant fish to reach the sea and glass eels and elvers to enter the lake,” Dr Town says. “It can also allow accumulated nutrients and pollutants to be flushed out and the influx of other fish species. “Because of the periodic opening to the sea the wet years should be beneficial to the lake’s eel fishery and the dry years detrimental. The continuing decline in the Lake Ellesmere eel fishery may require four measures.” The first of these is a substantial reduction in the total allowable catch, possibly to a level of 15 to 50 tonnes a year. Dr Town also suggests the possibility of closing the eel fishery until clear signs of stock recovery become evident.

Closure of the fishery for feeder eels is another possible measure, along with abandoning close management of the eel fishery. This latter measure would allow fisher-

men to harvest a mixed wetfishery in the lake with eels forming a part of it. “It is possible that the continued eel fishing effort in Lake Ellesmere, coupled with poor water quality, will lead to the commercial extinction of this fishery,” Dr Town says. “Or else it could lead to a stock level that will support far fewer permit holders.”

Commercial freshwater eel fishing is the most productive and lucrative of New Zealand’s exportbased commercial freshwater fisheries. In 1984, eel exports earned $3.45 million and were the nineteenth most valuable fish export product.

“The country has very few commercial freshwater fisheries and only eels, grey mullet, yellow-eyed mullet, flounder, and whitebait are taken in significant commercial quantities. The eel fishery is based on two species, the longfin eel and the shortfin eel which both occur throughout New Zealand.

“There was little interest in commercial eel fishing until about 20 years ago and commercial catches remained below 100 tonnes per annum until 1967. In the last four years both reported catches and export tonnages have remained close to 1000 tonnes per annum.”

The Netherlands, West Germany, Belgium, France, and Britain form the principal markets for live eels, frozen or fresh chilled fillets, smoked, dried, in brine, and canned eels.

“Virtually all the commercial eel catch is taken with Fyke nets,” Dr Town says. “These are often baited and set in rows overnight to take

advantage of the eel’s nocturnal habits.”

Of the 285 permits issued to eel fishermen in New Zealand, 11 are held for Lake Ellesmere, four for Marlborough, 15 for Westland, 11 for North Canterbury, five for South Canterbury, and one for the Chatham Islands. “Commercial eel catches are reported from 22 separate areas in New Zealand, their boundaries corresponding with those of the catchment authorities. The success of flood control works in many parts of the country has had a major impact on the eel fishery,” Dr Town says.

“In general, eel fishing tends to peak at the time when floods and freshes recede. As flood events become more rare this peak fishery has tended to decline.” Almost without exception, New Zealand’s hydro-electric dams have prevented upstream migration of elvers, Dr Town says. “Once eels have been fished out or have migrated from these impounded areas the water become essentially eel-free. “The stress evident in some eel fishing areas requires a new, coherent, and rational management package. Such a package needs to be discussed with the commercial eel industry so that measures implemented are well understood.” A spokesman for the Lake Ellesmere Commercial Fishermen’s Association says that the report’s options for Lake Ellesmere are under discussion. He is confident that a new agreement, satisfactory to both the fishermen and the fisheries management division, for the control of commercial eel fishing, can be reached.