Whether lobster conservation makes money for fishermen or costs them money depends on the choice of conservation measure.

The same biological result can be achieved by measures that have very different economic impacts.

The establishment of a maximum legal size limit for lobsters, compared to an increase in the minimum legal size, compared to v-notching of female lobsters, compared to a reduction in fishing effort, all provide good examples of the varying economic impacts of different biological conservation tools.

Permanently protects a portion of the stock from harvest, thereby lowering the yield from the fishery. For the same amount of effort and cost, fishermen will catch less. If the fishery is catching lobsters so fast that few, if any, reach the maximum size, then there will be no impact on either conservation or the economics of the fishery.

The lobsters that are temporarily protected to allow them to produce eggs move into the legal catch after they grow. The yield from the fishery is increased by the growth of the lobsters minus any losses to natural mortality. Fishermen will catch more with the same effort and cost, up to a point. Economists have developed a tool called the "eumetric yield curve" to determine the appropriate combination of minimum size and fishing mortality rate to maximize the economic return from a fishery.

V-notching of female lobsters is used to counteract excessive fishing pressure. V-notched lobsters must be thrown back, thus decreasing the number of lobsters that lobstermen can land compared to the number that they catch. Whereas it costs money to catch a lobster, throwing lobsters back is not the most economical way to conserve the resource. It would be far better to reduce fishing effort so that the fleet did not catch as many lobsters, rather than catching them and throwing them back.

A reduction in fishing effort allows lobsters that otherwise would have been caught this year to escape capture and live, grow, and produce eggs until next year.

The growth of the lobsters that escape capture this year, but get caught next year, will increase the yield from the fishery. The reduction in fishing effort lowers costs, so lobstermen catch more at less cost, meaning more profit. (Requires that overall effort in the fishery be reduced. It is not effective to reduce the traps used by each fisherman, for example, if the total number of fishermen can increase.)