The fishery resources
off the northeastern United States are harvested by a variety
of fishing gears, including trawls, gillnets, handlines, traps,
pots, longlines, and dredges. While each type of gear captures
a different mix of species, few fishing operations target
just one species. The number of species caught varies by gear
type and area fished. In addition, predator-prey and competitive
relationships occur in almost all species.
These relationships
result in significant interactions among gear types (termed
technical interactions) and among species (termed biological
interactions). Management of fishing activity in the northeast
region is complex, in part owing to these types of interactions.
This complexity is reflected, for example, in the structure
of some of the fishery management plans (FMPs). The groundfish
fisheries off New England, comprising 15 species, are managed
under the Northeast Multispecies FMP (of the New England Fishery
Management Council), while several pelagic stocks are managed
under the Atlantic Mackerel, Squid, and Butterfish FMP of
the Mid Atlantic Fishery Management Council. The Atlantic
States Marine Fisheries Commission is responsible for stocks
which occur primarily in state waters such as lobsters, striped
bass, and bluefish.
While much of the stock assessment advice
used in managing these fisheries requires knowledge of the
dynamics of individual populations, there is an increasing
need to consider information in a more aggregated way as
fisheries management takes account of ecosystem impacts.
In this section, biomass and landings trends are presented
for several aggregated species groups to illustrate overall
changes in some of the fisheries resources off the northeastern
United States.
FISHERY INDEPENDENT DATA
The Northeast Fisheries
Science Center (NEFSC) has conducted an intensive bottom trawl
survey program off the northeastern United States for more
than 40 years. An autumn survey has been conducted annually
since 1963 and a spring survey was initiated in 1968. The
NEFSC surveys employ standard gear and sampling procedures
following a stratified random sampling design, and thus provide
a valuable time series of data for monitoring resource trends.
Although standard gear and vessels were used for most of the
time series, a different net, type of doors and a second vessel
were used when necessary (Sosebee and Cadrin 2006). Conversion
factors to the standard gear have been estimated for some
species (Sissenwine and Bowman 1982; NEFSC 1991). Since bottom
tending gear is used, the data are most appropriate for demersal
species, although reliable indices of abundance have also
been developed for several pelagic species.
AGGREGATE RESOURCE TRENDS
Biomass trends for seven
species assemblages are reviewed in this section. These are
as follows:
Principal
groundfish, which are mostly demersal species includes
Atlantic cod, haddock, pollock, Acadian redfish, silver hake,
and red hake that historically supported important offshore
trawl fisheries.
Flounders,
which includes all the major flatfish species including yellowtail
flounder, winter flounder, witch flounder, American plaice,
windowpane flounder, Atlantic halibut, and summer flounder.
Other groundfish,
which includes a variety of demersal species including
goosefish, black sea bass, white hake, tilefish, ocean pout,
cusk, scup, and Atlantic wolffish.
Principal
Pelagics, comprising Atlantic
herring and Atlantic mackerel.
Other Pelagics,
which includes such species as bluefish, butterfish,
blueback herring, alewife, and American shad.
Squids, comprising
two species of squid, Loligo pealeii and Illex
illecebrosus.
Small Elasmobranchs, which includes spiny
dogfish, barndoor skate, clearnose skate, little skate,
rosette skate, smooth skate, thorny skate and winter skate.
For each of these groups, an aggregate index of biomass
was developed to monitor resource trends. Autumn survey
data (stratified mean catch per tow, kg) were used for principal
groundfish, flounders, other groundfish, other pelagics
and squids while spring survey data were used for principal
pelagics and for small elasmobranches. Since the autumn
survey did not begin sampling in the Mid-Atlantic area until
1967, only data from 1967 to present are presented. For
each group, an aggregate biomass index was computed as the
sum of the individual species' stratified mean catch per
tow values, smoothed (LOESS smoother using 20 percent of
the data) to account for inter-annual variability. When
a conversion factor for a species/gear was significant,
it was used to adjust the index to the standard gear. No
adjustments have been made for differences in vulnerability
to the trawl gear by species.
Principal
Groundfish
The
annual index for this group declined between 1967 and 1974,
reflecting increases in exploitation associated with the
arrival of distant water fishing fleets (Figure
6[Fig
6 Data]). Declines in abundance occurred
for many stocks in this group, notably Georges Bank haddock
and Acadian redfish. Partial resource recovery occurred
during the mid to late 1970s, due in part to reduced fishing
effort associated with increasingly restrictive management
measures enacted by the International Commission for the
Northwest Atlantic Fisheries (ICNAF) during the early 1970s.
Cod and haddock abundance markedly increased, pollock biomass
sharply increased, silver and red hake were stable, and
Acadian redfish continued to decline. The smoothed aggregate
index peaked in 1977, but subsequently declined reaching
low values in 1987 and 1988. During 1989-1990, the aggregate
index increased slightly in response to improved recruitment
(primarily for cod, redfish, silver hake, and red hake),
but afterwards reached record low levels during 1992-1994.
Since the mid-1990s the index has been increasing due to
higher biomass levels of Georges Bank haddock and redfish.
In 2005, the index for the group was similar in magnitude
to that observed in the mid-1970s.
Figure
6
Flounders
The combined index for this group increased in the late
1960s, declined in the early 1970s, but recovered and
peaked in the late 1970s-early 1980s (Figure
7 [Fig
7Data]) due to reduced fishing effort associated with
increasingly restrictive management measures enacted by
the International Commission for the Northwest Atlantic
Fisheries (ICNAF) during the early 1970s. Most
of the northern flatfish species (yellowtail flounder,
American plaice, witch flounder and winter flounder) increased
during this time. Since the early 1980s,
the index has trended downward and was at near-record
lows in 2005.
Figure
7
Other
Groundfish
The aggregate index for this group increased through 1970,
remained relatively stable through 1980, (Figure
8 [Fig
8 Data]) and then declined through 1994. The index increased
in the late 1990s and early 2000s due to a high biomass
of scup, black sea bass and modest increases in white hake
biomass. However, the index declined in 2003 and 2004 and
in 2005 was near the time series low. Overall, the other
groundfish index declined by 70 to 80 percent during the
past 30 years reflecting increased exploitation of the individual
species within this group.
Figure
8
Principal
Pelagics
Biomass of Atlantic herring and Atlantic mackerel has been
monitored in NEFSC spring surveys since both species occur
almost completely within the survey area in March and April.
In general, survey catch per tow data for these two species
are more variable than for principal groundfish and flounders,
although the aggregate index adequately depicts overall
trends (Figure
9[Fig
9 Data]). The index dropped to extremely low levels
in the mid-1970s, reflecting pronounced declines in the
abundance of both species, including the collapse of the
Georges Bank herring stock. Between 1983 and 2000, the index
generally increased, peaking in 1998 and 2000 at near record
high values. Subsequently, the index has slightly declined.
Figure
9
Other
Pelagics
The aggregate index for other pelagics mainly reflects the
biomass of butterfish (Figure
10[Fig
10 Data]). The index was relatively low in the late
1960s through the early 1970s, increased in the late 1970s
and remained relatively stable for a decade, but has since
declined with the 2005 value the lowest in the time series.
Figure
10
Squids
The index for this group of species is dominated by the
biomass of the longfin inshore squid, Loligo pealeii
(Figure
11[Fig
11 Data]). The aggregate index has progressively declined
from its 1975 peak with some very brief increases occurring
about every decade.
Figure
11
Small
Elasmobranchs
The small elasmobranch biomass index includes data for two
important resource components, spiny dogfish and seven species
of skates, which are monitored using spring survey data
(Figure
12[Fig
12 Data]). This index increased from the late 1960s
through 1990, reflecting large increases in spiny dogfish
biomass, as well as increases in abundance of winter skate
and little skate. From 1990 through 2003, the index gradually
declined, reflecting reductions in biomass due to harvesting
of winter skate and spiny dogfish. The aggregate index has
increased since 2003 as restrictions on the exploitation
of spiny dogfish have allowed for some recovery of this
stock.
Figure
12
COMMERCIAL LANDINGS TRENDS
Prior to 1994, fishery
statistics in the Northeast Region were collected using
a voluntary reporting system. Landings and price data were
obtained by NMFS port agents and state personnel at the
point of first sale through dealer reports or "weighout
receipts". This information was complemented by dockside
interviews of vessel captains by NMFS port agents in which
detailed information was acquired on fishing effort, gear
used, and areas fished; and also by a monthly canvas to
collect landings data at secondary ports. In June 1994,
a mandatory reporting system was enacted in which dockside
interviews were replaced by a logbook reporting system.
This system is now used in all Northeast fisheries subject
to federal fishery management plans (except for the American
lobster and Atlantic herring fisheries). However, many vessels
that fish for lobster and herring possess permits under
one or more of the other federal plans, and are therefore
subject to mandatory reporting.
In this section, landings
trends are presented for eight species groups which closely
correspond to those used in the previous section on Aggregate
Resource Trends. Slight changes were imposed in order to
make the groupings the same as those found in the Species
Synopses section. Landings data for these groups were obtained
from records of U.S. domestic fishing activity and from
the database of reports of distant-water fleet catches maintained
by the Northwest Atlantic Fisheries Organization (NAFO).
These data cover the period from the early 1960s through
2005. Landings of most species are given in terms of nominal
catches, defined as live weight equivalent of landings.
Conversion factors for roundfish usually range from 1.1
to 1.2 but for bivalves (sea scallops, ocean quahogs and
surfclams), the conversion factors are 8.33, 8.25 and 5.24,
respectively. Therefore, the nominal catches of these 3
species are expressed in their meat weight equivalents so
the weights do not overshadow the finfish categories.
The eight groups are as
follows:
Principal groundfish:
Atlantic cod, haddock, pollock, Acadian redfish, silver
hake and red hake.
Flounders:
yellowtail flounder, winter flounder, witch flounder, American
plaice, windowpane flounder, Atlantic halibut and summer
flounder.
Other groundfish:
goosefish, black sea bass, white hake, tilefish, ocean pout,
cusk, scup, and Atlantic wolffish.
Principal pelagics:
Atlantic herring and Atlantic mackerel.
Other pelagics:
bluefish, butterfish.
Invertebrates:
Sea scallops, Ocean quahogs, surfclams, Loligo
squid, Illex squid, Northern shrimp and American
lobster.
Small elasmobranchs:
spiny dogfish, barndoor skate, clearnose skate, little skate,
rosette skate, smooth skate, thorny skate and winter skate.
Anadromous species:
river herring (alewife and blueback herring), American shad,
striped bass, Atlantic salmon.
SUMMARY
OF STOCK STATUS
For all eight groups combined, U.S. commercial landings
in 2005 totaled 363,223 mt, 11% lower than in 2004 (Figure
13[Fig
13 Data]).
U.S. commercial landings in each of the eight categories
have declined since the early 1960s. Total aggregate landings
were dominated by distant-water fleets during the 1960s
through the mid-1970s. Following implementation of extended
jurisdiction in 1977, landings have been primarily taken
by the U.S. domestic fleet.
Figure 13
Principal groundfish
annual landings decreased from a peak of over 650,000
mt in 1965 to about 200,000 mt through the mid-1970s,
declined to about 100,000 mt through the mid-1980s,
and have averaged about 40,000 mt since the mid-1990s.
During the 1960s and early 1970s, landings were dominated
by red hake and silver hake taken primarily by distant
water fleets. During subsequent decades, principal groundfish
landings were dominated by cod, pollock and silver hake.
Landings of haddock averaged between 50,000 and 100,000
mt annually during the mid-1960s, especially in 1965
and 1966 when distant-water fleets caught between 70,000
and 98,000 mt. USA haddock landings declined from over
50,000 mt per year during the mid-1960s to 3,000 to
5,000 mt during the mid-1970s, increased briefly during
the late 1970s, but have remained below 5,000 mt since
the mid-1980s.
Flounder
landings remained relatively stable, varying annually
between 60,000 and 70,000 mt during the early 1960s
through the mid-1980s. During this period, yellowtail
flounder dominated USA landings, but during the late
1980s were replaced by summer flounder and winter flounder.
In recent years, these two species, along with American
plaice, have accounted for the majority of the flounder
landings.
Landings of other groundfish
have remained relatively stable since the early 1960s,
generally averaging between 20,000 and 30,000 mt annually.
USA landings generally fluctuated between 15,000 mt and
25,000 mt during the early 1960s through the late 1980s.
Scup, and to a lesser extent, ocean pout dominated the
USA landings during the 1960s and 1970s, but were replaced
by goosefish and white hake during the late 1980s. USA
landings of other groundfish increased substantially during
the 1990s largely due to increasing landings of goosefish
which, since 1993, have accounted for 50% or more of USA
landings of other groundfish. Landings by distant-water
fleets were relatively minor compared to USA landings,
generally accounting for less than 2,000 mt annually except
for a few years during the 1960s when large catches of
ocean pout increased the total distant water fleet landings
of other groundfish to between 10,000 mt and 25,000 mt.
During the 1960s and
1970s, the fisheries for principal pelagics
were prosecuted primarily by distant-water fleets. Annual
landings increased throughout the 1960s as these fleets
directed fishing effort initially on Atlantic herring
and later during the 1970s on Atlantic mackerel. The international
fishery for Atlantic mackerel persisted through the mid-1980s
via domestic joint ventures with several countries, while
the domestic fishery focused on Atlantic herring. Total
landings of principal pelagics have increased steadily
since 1998 due, in large part, to increased USA landings
of Atlantic herring.
Landings of other
pelagics have remained relatively
stable since the early 1960s, generally averaging between
5,000 and 10,000 mt annually, with occasional annual landings
as high as 15,000 mt and 20,000 mt. Butterfish dominated
USA landings during the 1960s, but since 1970 commercial
landings of other pelagics, have been almost equally divided
between butterfish and bluefish. Landings by distant water
fleets were relatively minor except for a few years during
the 1960s and early 1970s when butterfish landings were
between 10,000 mt and 20,000 mt.
Landings of invertebrates
have generally varied between 100,000 mt and 150,000 mt
since 1970. Landings for this group peaked once during
the mid-1970s at over 133,000 mt and again beginning in
1989 at over 150,000 mt. Annual USA landings ranged from
50,000 to 70,000 mt during the 1960s and 1980s, and increased
to over 100,000 mt annually beginning in 1986. Total USA
landings remained relatively constant throughout the 1990s
and early 2000s, generally between 120,000 mt and 130,000
mt annually. USA landings were dominated by surfclams
and ocean quahogs throughout most of the period, with
surfclam landings consistently in the range of 20,000
to 30,000 mt of meats from 1963 onwards. Ocean quahog
landings became significant in 1978 as landings increased
to 10,000 mt of meats and since 1985 have fluctuated around
20,000 mt. Landings of sea scallops have been variable,
but generally ranged between 5,000 and 10,000 mt of meats
during the 1960s through the mid-1970s, and between 10,000
mt and 20,000 mt of meats since 1977. Longfin and shortfin
squids and American lobster also contributed between 10,000
and 20,000 mt during the 1980s and between 20,000 and
30,000 mt since the 1990s. Distant-water fleet landings
consisted primarily of almost equal amounts of longfin
and shortfin squid with combined landings of the two species
averaging over 20,000 mt during the 1970s and early 1980s,
peaking at almost 45,000 mt in 1973 and 1974. The remaining
non-USA landings consist primarily of Canadian harvests
of sea scallops, with landings generally between 4,000
and 10,000 mt of meats annually, primarily from the Canadian
fishery on the Northeast peak of Georges Bank.
Small elasmobranch
landings exhibit two peaks in the range of 20,000 mt to
30,000 mt, one in the mid-1970s due to distant water fleet
landings of spiny dogfish, and one during the 1990s due
to USA landings of spiny dogfish and several species of
skates. During the intervening years, total landings from
the small elasmobranch group generally were below 10,000
mt per year.
Reported landings of anadromous species
generally ranged from 20,000 mt to 60,000 mt during
the 1960s through the mid-1970s. During this period
alewives dominated both USA and distant-water fleet
landings. USA alewife landings have subsequently declined
and have averaged less than 500 mt annually since 1993.
Striped bass have also accounted for a substantial share
of USA anadromous species landings, contributing up
to about 5,000 mt during the 1960s and 1970s. Landings
of this species declined rapidly during the 1980s to
100 mt by 1989. Striped bass commercial landings subsequently
increased during the 1990s, and since 1998 have averaged
between 2,500 mt and 4,000 mt annually.
CONCLUSIONS ABOUT
RESOURCE ABUNDANCE
Both fishery-independent
and fishery-dependent data suggest major changes in
the abundance of resources in the Northwest Atlantic,
especially since implementation of the MFCMA in 1977.
Increases in abundance of groundfish and flounders associated
with the reduction of distant-water fleet fishing activity
during the mid-1970s were followed by increased domestic
fishing effort and landings. Biomass of both principal
groundfish and flounders began to decline after 1978,
reached record low levels in the early 1990s, and has
since improved for some species. Biomass of other groundfish
slowly declined after 1977, with more rapid declines
occurring in recent years. Biomass of principal pelagic
species declined rapidly after the period of extensive
fishing in the 1960s and 1970s but has sharply increased
in recent years. Extensive changes in the species composition
of the catches have also occurred over the past four
decades, with shifts to previously less desirable species.
During this same time, increases in the abundance of
historically non-targeted species such as spiny dogfish
and skates occurred, followed by the development of
directed fisheries for these species and subsequent
declines in the resource.
Most of the changes in abundance are directly attributable
to changes in fishing mortality. For example, increases
in biomass of groundfish and flounder occurred during
1975 to 1978 when fishing effort was being reduced by
international and domestic management actions. Decreases
in abundance began in the early 1980s when fishing effort
from domestic fleets substantially increased. The record
high levels of fishing effort in the late 1980s and
early 1990s resulted in rapid reduction of year classes
before they were able to achieve full growth and maturity.
Reductions in fishing effort, beginning in the mid-1990s
in the New England area, were followed by increases
in biomass of several groundfish and flounder stocks,
including haddock on Georges Bank and witch flounder
in the Gulf of Maine.
Figure
14
Each
of the individual species synopsis sections contains
a determination where possible of current stock
status with respect to a biomass threshold as
well as a fishing mortality threshold. The section
below provides an overview of all of the individual
species/stock status determinations. A stock is
considered to be overfished when the current estimate
of biomass is below the threshold of ½
Bmsy. Likewise, overfishing is occurring
on a stock if the current estimate of fishing
mortality is above the threshold of Fmsy.
Using this categorization scheme, 19 stocks are
considered to be overfished and 10 stocks are
currently experiencing overfishing. For 14 stocks,
neither their status with respect to not-overfished
or being overfished can presently be determined
and hence these stocks are classified as ‘Status
Unknown’.
Figure
14
provides a qualitative picture of all of the stocks
in one view. To obtain the specific details on
each stock, the following tables contain the most
current estimates of fishing mortality and biomass
or their proxies, and the corresponding reference
points used for status determination.
Improvements noted for some resource components in recent
years reflect recent management actions by the New England
and Mid-Atlantic Fishery Management Councils and the Atlantic
States Marine Fisheries Commission. Amendment 5 to the Northeast
Multispecies Fishery Management Plan was implemented in
1994 with a planned reduction in fishing effort by 50% over
5-7 years. Amendment 7 (implemented in 1996) permanently
closed large areas of fishery habitat and accelerated days-at-sea
effort reductions. Amendment 13, implemented in 2004, instituted
additional restrictions on fishing effort and imposed formal
rebuilding plans for those stocks considered to be overfished
at that time. These measures have resulted in reductions
in fishing mortality rates for four of the main New England
groundfish stocks (Georges Bank cod, Georges Bank haddock,
Gulf of Maine cod and witch flounder). Currently, Framework
42 to the FMP is aimed at further reductions in fishing
mortality to achieve stock rebuilding by restricting effort
in the areas where critical stocks are most vulnerable.
Other overfished components of the groundfish resource are
benefiting as well. Monkfish and spiny dogfish are now regulated
under Fishery Management Plans implemented in 1999 and 2000,
respectively.
Amendments 4, 5, and 6 to the Sea Scallop FMP were implemented
beginning in 1994 to replace meat count regulations with
direct controls on fishing effort (e.g., days at sea) and
gear selectivity. Also in 1994, three large areas, two on
Georges Bank and one on Nantucket Shoals, were closed to
scallop fishing under the groundfish plan. Scallop biomass
in these areas rapidly increased between 1994 and 2000,
and limited re-openings of portions of these areas in 1999-2001
and 2004-2006 have produced considerable landings. In the
Mid-Atlantic, three areas have been closed rotationally
to scallop fishing (with each area closed for about three
years) since 1998 in order to improve yield, and a fourth
area is scheduled for closure in 2007. Other major management
measures include Amendment 7, implemented in 1999, that
established reference points and implemented a rebuilding
plan for the sea scallop resource. Amendment 10, implemented
in 2004, formally adopted area management and rotational
closures and further increased dredge ring and twine top
size to shift gear selectivity toward larger scallops and
to reduce finfish bycatch.
Management programs for summer flounder have been successful
in reducing exploitation levels, although fishing mortality
still exceeds the threshold reference point. The quota-based
system of management has resulted in a series of trip limits,
and state-by-state closures as the quota is approached.
The time schedule adopted by the Mid-Atlantic Fishery Management
Council calls for additional reductions in mortality to
broaden the age distribution within the stock and reach
the target spawning stock biomass by 2013.
A joint management plan for bluefish between the Mid-Atlantic
Fishery Management Council (MAFMC) and the Atlantic States
Marine Fisheries Commission (ASMFC) was implemented in 1990.
The basis for management is an annual quota subdivided between
recreational and commercial fisheries. Management actions
have resulted in a decrease in fishing mortality and an
improvement in bluefish biomass, although biomass levels
require further improvement to reach the target level.
Other fishery management programs are currently being developed
to address overfishing of inshore stocks (winter flounder,
weakfish, scup and others) primarily under the jurisdiction
of the ASMFC and individual states. A summary of fishery
management plans currently in place is given in Table
1.
Anon. 1998a. Improving Fish Stock Assessments.
Committee on Fish Stock Assessment Methods. Ocean Studies
Board. National Research Council. National Academy Press,
Washington, D.C., 177 p.
Anon. 1998b. Review of Northeast
Fishery Stock Assessments. Committee to Review Northeast Fishery
Stock Assessments. Ocean Studies Board. National Research
Council. National Academy Press, Washington, D.C., 128 p.
Brown, B.E., J.A. Brennan,
E.G. Heyerdahl, M.D. Grosslein and R.C. Hennemuth. 1976. The
effects of fishing on the marine finfish biomass of the Northwest
Atlantic from the Gulf of Maine to Cape Hatteras. ICNAF Res.
Bull. 12: 49-68.
Clark, S.H. and B.E. Brown.
1977. Changes in biomass of finfish and squids from the Gulf
of Maine to Cape Hatteras, 1963-1974, as determined from research
vessel survey data. Fish. Bull., U.S. 75(1):1-21
Mayo, R.K, M.J. Fogarty,
and F.M. Serchuk. 1992. Aggregate fish biomass and yield on
Georges Bank. J. of Northwest Atl. Fish. Sci. 14:59-78.
NEFC. 1991. Report of the
Twelfth Northeast Regional Stock Assessment Workshop (12th
SAW). Northeast Fisheries Science Center Ref. Doc. 91-03,
187 p.
Sissenwine, M.P., and E.
Bowman. 1978. An analysis of some factors affecting the catchability
of fish by bottom trawls. Int. Comm. Northw. Atl. Fish. Res.
Bull. 13: 81-87.
Sosebee, K.A., and S.X.
Cadrin. 2006. A Historical Perspective on the Abundance and
Biomass of Northeast Demersal Complex Stocks from NMFS and
Massachusetts Inshore Bottom Trawl Surveys, 1963-2002. Northeast
Fisheries Science Center Ref. Doc. 06-05, 200 p.
