Kyne & Simpfendorfer.. - Shark Specialist Group

Table 2.13. Age and growth of arhynchobatid skates. von Bertalanffy growth model (VBGM)
parameters: L ∞ (mm TL or DW), k (year -1 ), t 0 (years); t max oldest fish (years), A mat age at
maturity (years).
Species
Location
VBGM parameters
t max A mat Reference
L ∞ k t 0
Bathyraja
albomaculata
Falkland/Malvinas
Is., SW Atlantic
♀ 649mm DW
♂ 706mm DW
0.09
0.07
-1.94
-2.39
17
17
10
11
Henderson et al.
(2004)
Falkland/Malvinas
Is., SW Atlantic
♀ 1112mm TL
♂ 953mm TL
0.048
0.060
-3.9
-3.8
--
--
14.4
12.5
M. Gallagher (pers.
comm.)
Bathyraja
brachyurops
Falkland/Malvinas
Is., SW Atlantic
♀ 1204mm TL
♂ 1311mm TL
0.07
0.05
-1.95
-2.55
16
18
11.12
11.55
P. Brickle (pers.
comm.)
Falkland/Malvinas
Is., SW Atlantic
♀ 1301mm TL
♂ 1296mm TL
0.060
0.058
-2.2
-2.1
--
--
11.7
10.1
M. Gallagher (pers.
comm.)
Bathyraja
griseocauda
Falkland/Malvinas
Is., SW Atlantic
♀ 3652mm TL*
♂ 3589mm TL*
0.02
0.02
-3.46
-3.04
29
20
18.10
15.26
P. Brickle (pers.
comm.)
Falkland/Malvinas
Is., SW Atlantic
♀ 3029mm TL
♂ 2197mm TL
0.022
0.034
-2.6
-2.2
--
--
23.7
18.3
M. Gallagher (pers.
comm.)
Bathyraja
parmifera
Eastern Bering Sea,
North Pacific
♀ 1446mm TL
♂ 1263mm TL
0.09
0.12
-1.75
-1.39
17
15
10
9
Matta & Gunderson
(in press)
Bathyraja
scaphiops
Falkland/Malvinas
Is., SW Atlantic
♀ 1196mm TL
♂ 1296mm TL
0.063
0.058
-1.9
-2.1
--
--
13.5
9.0
M. Gallagher (pers.
comm.)
*The estimates of L ∞ for B. griseocauda are inflated (max size of species ~2000mm TL).
Family Rajidae. Hardnose Skates.
There is considerably more information available in the biology of the hardnose skates than
most other batoid families, particularly for shelf species. Overall though, the knowledge of
this family, the most speciose of all the deepwater chondrichthyan families, remains poor. As
with the arhynchobatids, the systematics of the family are not yet resolved, and there remains
many undescribed species (19% of deepwater species). The family contains the deepest
recorded chondrichthyan fish, Bigelow's skate Rajella bigelowi which has been recorded to
4156m depth (Stehmann 1990) (Amblyraja are also amongst the deepest, reaching ~2600m
depth). The majority of available information on hardnose skates is derived from the North
Atlantic and North Pacific, but there is also a growing body of work from southern regions
including New Zealand, South America and the Antarctic.
Reproductive and age and growth parameters for hardnose skates are summarized in Tables
2.14 and 2.15, respectively.
Like the softnose skates, reproductive activity appears to occur year-round and this has been
demonstrated for such species as the smooth skate Malacoraja senta and the thorny skate
Amblyraja radiata (Sulikowski et al. 2005b, 2007). Again, as with other oviparous families,
fecundity estimates are difficult and there is little ovarian fecundity information for the
deepwater hardnose skates. Two species of rajid are known to carry multiple embryos per egg
case, the mottled skate Raja pulchra, an inshore coastal species from the Northwest Pacific,
and the big skate R. binoculata from the eastern North Pacific (Ishiyama 1958, Hitz 1964,
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