The butterfish, Peprilus triacanthus, is a
small, bony foodfish weighing up to 0.5 kg, with a thin oval body. Butterfish
short-lived and grow rapidly. Few live to more than 3 years of age, and
most are sexually mature at age 1. Butterfish range from Florida to Newfoundland,
but are primarily found from Cape Hatteras to the Gulf of Maine where
the population is considered to be a unit stock (Figure
The Butterfish migrate in response to seasonal changes
in water temperature. During summer, butterfish move northward
and inshore to feed and spawn. Spawning occurs during June to
August, and peaks progressively later at higher latitudes. During
winter, butterfish move southward and offshore to avoid cool waters.
Butterfish are primarily pelagic, and form loose schools that
feed upon small fish, squid, and crustaceans. Butterfish have
a high natural mortality rate and are preyed upon by many species
including silver hake, bluefish, swordfish, and long-finned squid.
During summer, juvenile butterfish associate with jellyfish to
The butterfish stock is
managed using annual quotas under the Mid-Atlantic Fishery Management
Council's Atlantic Mackerel, Squid, and Butterfish Fishery Management
Plan. The information provided herein reflects the results of
the most recent peer-reviewed assessment for the butterfish stock
landings of butterfish increased in the late 1960s and early 1970s
due to distant water fleet fisheries and total landings peaked
at 34,300 mt in 1973 (Figure
24.2 Data]). Discards of butterfish in fisheries targeting
other species can be considerable and annual estimates have recently
averaged between 1,000-9,200 mt (Table 24.1).
US commercial landings, which averaged 3,200 mt per year during
1965-2002, peaked at 11,972 mt in 1984. Since 1985, landings declined
and in 2005 were 432 mt, at record-low (Table
Research Vessel Survey
Biomass indices in NEFSC spring research
vessel surveys were generally higher in the early 1970s and mid
1980s than in the late 1980s and early 1990s. (Figure
24.3 Data]). The spring survey indices increased in the late
1990s but then declined slightly and have since been stable. NEFSC
autumn biomass indices exhibited large fluctuations during 1980-2000
but have since declined to record low levels. Age groups 0-2 are
common in the surveys, with the age 0 catch dominating in number.
Very few 3 and 4 year olds were in the survey catches (Figure
Average fishing mortality estimates (age 1+,
unweighted) have fluctuated between 0.12 and 0.65 since 1980
and was 0.34 in 2002 (Figure
24.5 Data]). Spawning biomass has fluctuated between 7,800-62,900
mt during 1968-2002 and has declined since 1980. In 2002 spawning
biomass was 8,700 mt, one of the lowest values in this time
24.6 Data]). Recruitment biomass has also been highly variable,
varying between 10,000-50,000 mt (Figure
24.6 Data]). The 2001 and 2002 year class are among the
Yield reference points were last estimated
in the 1983 assessment (Waring and Anderson 1983) and are shown
in Table 24.2.
The SSB-recruitment plot for butterfish shows
that recruitment is highly variable over a wide range in SSB
for 10,000-50,000 mt (Figure
24.7 Data]). Survival ratios for butterfish were generally
high in the 1970s, low in the 1980s, and relatively high in
the 1990s (Figure
[Fig 24.8 Data]).
New MSY reference points were estimated
in the most recent assessment conducted in 2003 (NEFSC 2004).
A Fox model of surplus production for 1965-2002 produced an
MSY = 12,175 mt (including discards), Bmsy= 22,798
mt, and Fmsy= 0.38. However, there is considerable
uncertainty in these estimates.