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Table 6.3. Atlantic
cod EFH -- vulnerability to effects of
bottom-tending fishing gears and rationale for evaluations
| Life Stage |
Geographic Area of EFHa |
Depth (m) |
Seasonal Occurrence |
EFH Description |
EFH Vulnerabilityb |
| Otter Trawl |
New Bedford- Style Scallop Dredge |
Hydraulic Clam Dredge |
Pots and Traps |
Sink Gill Nets and Bottom Longlines |
| Eggs |
GOM,
GB, eastern portion of continental shelf off SNE, and following
estuaries: Englishman/ Machias Bay to Blue Hill Bay, Sheepscot
R., Casco Bay, Saco Bay, Great Bay, Massachusetts Bay, Boston Harbor, Cape
Cod Bay, and Buzzards Bay |
<110 |
Begins
in fall, peaks in winter and spring |
Surface
waters |
NA |
NA |
NA |
NA |
NA |
| Larvae |
GOM,
GB, eastern portion of continental shelf off SNE and following
estuaries: Passamaquoddy Bay to
Penobscot Bay, Sheepscot R., Casco Bay, Saco Bay,
Great Bay, Massachusetts Bay, Boston Harbor, Cape Cod Bay, and Buzzards Bay |
30-70 |
Spring |
Pelagic
waters |
NA |
NA |
NA |
NA |
NA |
| Juveniles |
GOM,
GB, eastern portion of continental shelf off SNE and following
estuaries: Passamaquoddy Bay to Saco Bay, Massachusetts
Bay, Boston Harbor,
Cape Cod Bay,
and Buzzards Bay |
25-75 |
|
Bottom
habitats with a substrate of cobble or gravel |
H |
H |
0 |
L |
L |
| Adults |
GOM,
GB, SNE, middle Atlantic south to Delaware Bay and following estuaries: Passamaquoddy Bay to Saco
Bay, Massachusetts Bay, Boston Harbor,
Cape Cod Bay,
and Buzzards Bay |
10-150 |
|
Bottom
habitats with a substrate of rocks, pebbles, or gravel |
M |
M |
L |
L |
L |
| Spawning
adults |
GOM,
GB, SNE, middle Atlantic south to Delaware Bay and following estuaries,
Englishman/ Machias Bay to Blue Hill Bay; Sheepscot R., Massachusetts Bay, Boston Harbor, and Cape
Cod Bay |
10-150 |
Spawn
during fall, winter, and early spring |
Bottom
habitats with a substrate of smooth sand, rocks, pebbles, or gravel |
M |
M |
L |
L |
L |
| Rationale: Atlantic cod (Gadus morhua) are distributed regionally
from Greenland to Cape
Hatteras , from nearshore to depths >400 m. In U.S. waters, they are
concentrated on GB and in the GOM, on rough bottom from 10-150 m (Fahay et al.
1999; Klein-MacPhee 2002a). Eggs and larvae are pelagic, so EFH
vulnerability is not applicable. Juvenile cod are found mostly in nearshore shoal waters or on offshore banks. Cobble is preferred over finer grained
sediments, and this life stage appears to use benthic structure and cryptic
coloration to escape predation (Fahay et al. 1999). Juvenile cod may benefit, perhaps strongly,
from physical and biological complexity (Lindholm et al. (2001); see discussion in
Chapter 2 of this document). Otter trawls and scallop dredges have been shown
to reduce habitat complexity (see Chapter 5), therefore EFH vulnerability to
these gear types was rated as high since the gear may affect the functional
value of EFH for this life stage. Vulnerability to clam dredges was rated as none since this gear is not
operated in juvenile cod EFH (see Chapter 4). Adults and spawning adults
occupy a variety of hard-bottom habitat types, including rock, pebbles, and gravel,
and tend to avoid finer sediments. Cod
eat a wide variety of prey, including fish, decapod
crustaceans, amphipods, and polychaetes (Fahay et al. 1999). Although adult cod are primarily found on
rough bottom, the scientific literature does not indicate that this habitat
type serves the same function as it does for juvenile cod. Based on the variable diet and lack of
evidence for direct functional value of benthic habitat, EFH vulnerability to
otter trawls and scallop dredges was rated as moderate. Adult cod may use areas where clam dredges
operate, such as the nearshore waters of New Jersey, on a
seasonal basis. Clam dredges operate only in sand (NREFHSC 2002), and the
recovery of benthic communities from the effects of clam dredging in nearshore, sandy habitats is rapid (Table 5.15). Clam beds are not chronically disturbed by
dredging since the population of clams, which are benthic infauna, must
recover before fishing is again profitable (NREFHSC 2002). Based on this information and the rationale
described for otter trawls and scallop dredges, habitat vulnerability for
hydraulic clam dredges was rated as low. EFH vulnerability for adults applies to spawning adults as well.
a EFH Geographic Areas: GOM = Gulf of Maine;
GB = Georges Bank; and SNE = Southern New England.
b EFH
Vulnerability Category (derived from the matrix analysis in Table 6.1): NA =
not applicable; 0 = no vulnerability; L = low vulnerability; M = moderate
vulnerability; and H = high vulnerability. |
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