So you want to know: Why do we v-notch lobsters?

First published in the MLA Newsletter, January, 2012

Since the mid-1980s, Maine landings have exploded from an annual average catch of 20 million pounds to the 95 million pounds landed in 2010. With such high landings, the practice of v-notching has become very important to scientists as one means to explain the continued high lobster population in the Gulf of Maine. A longstanding and accepted practice of the Maine lobster fishery, v-notching is a cornerstone of conservation and management.

V-notching is one of the few mechanisms that puts a legal lobster back on the bottom. It reduces the catch and exploitation of females while increasing potential egg production. Studies provide evidence that cutting a v-notch does not introduce disease or increase the mortality of lobsters. From its start in 1917 as a state-based purchase program of egg-bearing females, v-notch regulations evolved to the present day practice that is part of the daily routine of Maine lobsterman. Acceptance and compliance with v-notching regulations has increased steadily over the years.

In 2001, Lobster Management Area 1 received conservation credit and avoided management actions, such as changes to the gauge and trap limits, after the Atlantic States Marine Fisheries Commission (ASMFC) assessment model deemed that lobsters were overfished. Instead, mandatory v-notching and zero tolerance enforcement were adopted in Area 1. Although other states have been skeptical of v-notching, most Lobster Management Areas have adopted at least a 1/8-inch v-notch definition. Over time, the v-notch practice as a conservation measure has gained more credit within the ASMFC lobster assessment process.

Yet on the water, fishermen often complain about the large number of v-notched lobsters they haul. We know from research conducted by Maine DMR that a number of smaller lobsters thrown back because of v-notches or mutilations likely have never carried eggs. This is good for the lobster industry. The Area 1 legal minimum size of 3.25 inches is smaller than the estimated size of 50% of mature lobsters (3.58 inches). The only thing other than v-notching that keeps those lobsters from being harvested is natural mutilations. In other words, v-notching allows more females to grow larger and reproduce.

Surveys carried out by the MLA and Maine DMR give added weight to the practice of v-notching. Since 1982, MLA members have collected v-notch information during an annual two-day survey in October. Since 1985, Maine DMR has collected data on the discarded portion of the commercial catch through an at-sea sampling program. Although landings have more than quadrupled since the early 1980s, these two surveys have consistently found that an average of 70% of eggers hauled up in traps are already notched. This is evidence of high compliance with v-notching thus the existence of repeat spawners and large egg potential. V-notching permits breeders to pass through the gauntlet of the commercial harvest until they find refuge beyond maximum size.

Some lobstermen express concern over the potential to introduce disease or the risk of killing a lobster as a result of cutting a v-notch. Research conducted in 1987 found that a new v-notch did not increase the susceptibility to “red tail,” a disease commonly found in pounds. Deangelis, et al, in 2010 established that mortality is not significantly increased in notched lobsters.

V-notching has become a major part of the conservation measures in the ASMFC American lobster management plan. V-notching increases the yield of the fishery by enhancing recruitment and reduces the biomass available for harvest thus indirectly reducing fishing mortality. It ensures that there remain a large number of parents in the lobster stock which likely adds to the sustainability of the population.