The Atlantic herring, Clupea harengus,
is widely distributed in continental shelf waters of the Northeast
Atlantic, from Labrador to Cape Hatteras. Important commercial
fisheries for juvenile herring (ages 1 to 3) exist along the coasts
of Maine and New Brunswick. Development of large-scale fisheries
for adult herring is comparatively recent, primarily occurring
in the western Gulf of Maine, on Georges Bank, and on the Scotian
Shelf. Gulf of Maine herring migrate from summer feeding grounds
along the Maine coast and on Georges Bank to southern New England
and Mid-Atlantic areas during winter, with larger individuals
tending to migrate farther distances. Tagging experiments provide
evidence of intermixing of Gulf of Maine, Georges Bank, and Scotian
Shelf herring during different phases of the annual migration.
Spawning in the Gulf of Maine
occurs during late August-October, beginning in northern locations
and progressing southward. Atlantic herring are not fully mature
until age 4. Age at maturity varies annually and appears to change
in response to density dependent effects. Herring eggs are demersal
and are typically deposited on gravel substrates. Primary spawning
locations off the northeastern United States are located on the
Maine coast, Jeffreys Ledge, Nantucket Shoals, and Georges Bank.
Incubation is temperature dependent, but usually occurs for 7
to 10 days. Larvae metamorphose by late spring into juvenile brit
herring that may form large aggregations in coastal waters during
summer. By age 2, juvenile herring are fully vulnerable to fixed
and mobile gear coastal fisheries.
In the past, the herring resource along the
East Coast of the United States was divided into the Gulf of Maine
and Georges Bank stocks. There is currently no genetic evidence
to suggest that these two components are separate stocks. However,
morphometric analyses suggest that discernable phenotypic differences
exist among herring from the Gulf of Maine, Georges Bank, and
the Scotian shelf. However, fishery-independent measures of abundance
for herring include fish originating from all spawning areas.
As a consequence, herring from the Gulf of Maine and Georges Bank
components are combined for assessment purposes into a single
coastal stock complex (Figure
22.1). This approach has many advantages over
the separate stock approach, but also poses a number of technical
and management challenges, particularly for the management of
the smaller inshore component.
An interstate fishery management plan has been
adopted by the Atlantic States Marine Fisheries Commission (ASMFC),
and a Fishery Management Plan has been developed by the New England
Fishery Management Council (NEFMC) in collaboration with the ASMFC.
Management measures include spawning area closures, an area management
scheme (three areas), catch controls on the entire complex, and
a TAC on the near shore (1A) Gulf of Maine fishery. The information
provided herein reflects the results of the most recent peer-reviewed
assessment for the Gulf of Maine-Georges Bank herring complex
Total landings for the coastal
stock complex have declined from 470,000 mt in 1968 to 36,000
mt in 1983. (Table 22.1,Figure
22.2 Data]). After the large offshore fishery collapsed in
1977, the fishery focused on near shore waters of the Gulf of
Maine. Landings gradually increased from the mid 1980s through
the 1990s and peaked at 133,000 mt in 2001. Landings declined
slightly during 2002-2005, averaging 109,000 mt. The USA has accounted
for about 72% of landings since 1978, but during the last decade
has accounted for 85% of the total herring.
The fishery in the Gulf of
Maine consists of fixed and mobile gear fisheries in coastal waters.
Landings from the New Brunswick weir fishery ranged from 9,000
to over 44,000 mt during 1980-1998, while the mobile gear (purse
seine and mid-water trawl) fisheries landed between 27,000-81,000
mt during the same period. There has been a great deal of annual
variability in the landings, but little evidence of any long-term
trend. However, changes have occurred in the distribution of landings
between mobile and fixed gear fleets. Over the past five years,
greater than 90 percent of Maine herring landings have been taken
by U.S. mobile gear fisheries compared with less than 50 percent
during the 1970s. This shift reflects reduced availability of
herring to the fixed-gear fisheries and also less emphasis on
this type of fishing. Current mobile gear landings are dominated
by single and paired mid-water trawlers.
The Georges Bank herring fishery
was initiated in 1961 by distant-water fleets. Landings peaked
in 1968 at 373,600 mt and subsequently declined to 43,500 mt in
1976 as the fishery collapsed. Mid-water trawling by both USA
and Canada herring fleets began in 1994, with landings peaking
at 35,000 mt in 2001 and averaging about 13,000 mt during 1994-2005.
The majority of Georges Bank herring landings are by USA mid-water
vessels, with the balance taken by Canada.
Historically many age groups
of herring (age 2-7) have been represented in the commercial landings
22.3 Data]), as the inshore fisheries by the USA and Canada
focused on younger fish while the offshore distant water fisheries
targeted all age groups. After the offshore component had collapsed
in the late 1970s and early 1980s, and the inshore component had
been heavily fished, only age groups 2-3 were well represented
in the landings. As the herring complex recovered in the late
1980s and the offshore fishery resumed, the age distribution of
the landings expanded and ages 2-7 were prevalent. The recent
fishery has been dominated by the strong 1994 and 1998 year classes,
but many other recent cohorts have been moderate size or larger.
Biomass indices of herring in
NEFSC spring and autumn research vessel surveys were relatively
low during the 1960s and 1970s (Figure
22.4 Data]). and declined even further in the late 1970s and
early 1980s after the offshore component collapsed and the inshore
component was greatly reduced. The survey indices markedly increased
in the mid 1980s and early 1990s as recovery commenced, and have
since remained relatively high although variable.
NMFS surveys have shown a progressively
expanding age structure of herring in the Gulf of Maine-Georges
Bank region since the early (Figure
Estimates of total stock biomass
for the coastal stock complex exceeded 1 million mt before the
collapse of the Georges Bank fishery. After the collapse in the
early 1980s, stock size estimates declined to about 100,000 mt.
Stock biomass has since increased substantiality primarily due
to improved recruits. The offshore spawning component, which was
the largest historic component of the stock complex, is now fully
Fishing mortality (2+) for
herring declined from about 0.7 during 1970s to an average of
0.3 during the mid-late 1980s (Figure
22.6 Data]). Thereafter, fishing mortality declined 0.1 in
1998 and has since remained at this level. Total biomass (2+)
increased from about 105,000 mt in 1982 to about 1.3 million mt
in 2000 but declined to 1.0 million mt in 2005 (Figure
22.7 Data]). The increase in biomass the late 1990’s
was primarily due to generally improved recruitment and two extremely
large year classes, the 1994 and 1998 cohorts (Figure
22.7 Data]). The 1994 year-class was the largest at about
7.2 billion, followed by the 1998 year class at about 5.5 billion
and the 2002 year class at about 4.8 billion. Recruitment from
the 1999-2000 and 2003 year classes is weaker than average.
Yield per recruit reference
points were estimated as: F0.1= 0.21 and F40%=
0.20 (Table 22.2).
The relationship between spawning
biomass (SSB) and recruitment for the Gulf of Maine-Georges Bank
herring complex during 1967-2003 and the geometric mean recruitment
(horizontal line) are shown in (Figure
22.8 Data]). Near average or better than average recruitment
appear to occur at SSBs greater than about 700,000 mt. Recruit
per spawner ratios were relatively high during the 1980s. Recent
ratios have been greater than 1.0 (Figure
MSY reference points for the
herring complex were re-estimated during the most recent (2006)
assessment (Table 22.2). Results from a
Fox surplus production model were Fmsy = 0.31, MSY
= 194,000 mt, and Bmsy = 629,000 mt.
The Gulf of Maine-Georges Bank
herring complex began to recover during the late 1980s and current
total biomass (age 2+) is now comparable to the 1960s. Biomass
increased from a low of about 105,000 mt in 1982 to near 1.3 million
mt in 2001, and declined slightly to about 1.0 million mt in 2005,
but is still substantially above the BMSY (629,000
mt). Fishing mortality has remained low since the early 1990s
and has averaged 0.1 since 2002 far below FMSY (0.31).
The stock complex is not overfished and overfishing is not occurring.
Anthony, V. C., and G. Waring.
1980. The assessment and management of the Georges Bank herring
fishery. Rapp. P.-V. Reun. Cons. Int. Explor. Mer 177:72-111.
Fogarty, M. J., and S. H. Clark.
1983. Status of herring stocks in the Gulf of Maine region for 1983.
Northeast Fish. Sci. Cent. Ref. Doc. 83-46. 33 p.
Overholtz, W.J., and K.D. Friedland.
2002. Recovery of the Gulf of Maine-Georges Bank Atlantic herring
(Clupea harengus) complex: perspectives based on bottom
trawl survey data. Fishery Bulletin, 100: 593-608.
Smith, W. G. and W. W. Morse. 1993. Larval distribution patterns:
early signals for the collapse/recovery of Atlantic herring, Clupea
harengus, in the Georges Bank area. Fish. Bull., U.S. 91:338-347.