Distribution, Biology and Management

The white hake, Urophycis tenuis, occurs from Newfoundland to Southern New England and is common on muddy bottom throughout the Gulf of Maine (Bigelow and Schroeder 1953; Klein-MacPhee 2002) (Figure 18.1). Depth distribution of white hake varies by age and season; juveniles typically occupy shallower areas than adults, but individuals of all ages tend to move inshore or shoalward in summer, dispersing to deeper areas in winter (Musick 1974; Markel et al. 1982). Most trawl catches are taken at depths of 110 m (60 fathoms) or greater, although hake are taken as shallow as 27 m (15 fathoms) by gillnetting. Small white hake are difficult to distinguish from red hake, Urophycis chuss, resulting in a small degree of bias in reported nominal catches (Mayo and Terceiro 2005).

Larval distributions indicate the presence of two spawning groups in the Gulf of Maine, Georges Bank and Scotian Shelf region, one which spawns in deep water on the continental slope in late winter and early spring, and a second which spawns on the Scotian Shelf in the summer (Fahay and Able 1989; Lang et al. 1994). Populations in

U.S. waters appears to be supported by both spawning events, but individuals are not distinguishable in commercial landings. White hake attain a maximum length of at least 135 cm (53 in.) and weights of up to 21 kg (46 lb), with females being larger (Klein-MacPhee 2002). Ages up to 15 years have been documented (NEFSC 1999). Juveniles feed primarily upon shrimp and other crustaceans, but adults feed almost exclusively on fish, including juveniles of their own species (Bowman, 1981; Bowman et al. 1987; Bowman et al. 2000).

The Fishery

U.S. landings have primarily been taken in the western Gulf of Maine, both incidentally in directed fisheries for other demersal species and as an intended component in mixed species fisheries. Since 1968, U.S. landings have accounted for approximately 90 percent of the Gulf of Maine-Georges Bank white hake catch (Table 18.1). Canadian landings averaged 600 mt from 1977-1991, increased to 1,700 mt in 1993, but have since declined to less than 100 mt.

Total landings of white hake increased from about 1,000 mt during the late 1960s to 8,300 mt in 1985 (Figure 18.2 [Fig 18.2 Data]). Landings then declined to 5,100 mt in 1989, rose sharply to 9,600 mt in 1992, and have since steadily declined to levels not seen since the early 1970s. Landings of white hake subsequently increased to 4,400 mt in 2003, but declined to 3,600 mt in 2004.

Research Vessel Survey Indices

The NEFSC autumn bottom trawl survey biomass index fluctuated about a relatively high level during the 1970s and 1980s but declined during the 1990s, falling to near record low in 1999 (Figure 18.3 [Fig 18.3 Data]). The biomass index increased between 2000 and 2002 because of the recruitment of a good 1998 year class (NEFSC 2001), but has since declined to a very low level. The NEFSC spring survey biomass indices are more variable than the autumn, but declined during the 1990s, increased in the early 2000s, but have since declined.

Figure 18.3

Figure 18.4

Figure 18.5

Figure 18.6

Figure 18.7

Figure 18.8

The 2004 autumn survey biomass index of 3.01 kg/tow was below that of ½ B_msy (3.35 kg/tow) indicating that the stock is overfished (Figure 18.8 [Fig 18.8 Data]). Likewise, the relative F value of 1.18 in 2004 was above F_msy indicating that overfishing is still occurring (Figure 18.7 [Fig 18.7 Data]).

Table 18.1 Recreational and commercial landings of white hake (thousand metric tons).

Table 18.2 MSY-based reference points for Gulf of Maine/Georges Bank white hake.