PELAGIC FISHES
FOR SHALLOW DIVERS– THE
ONLY GAME IN TOWN
JOSE TORRES
SOUTHERN OCEAN FISHES
• TWO FUNDAMENTALLY DIFFERENT
TYPES
– OCEANIC FISHES WITH AFFINITIES TO
PELAGIC COMMUNITIES WORLDWIDE
– ANTARCTIC ENDEMICS ASSOCIATED
WITH COASTAL WATERS: USUALLY
BENTHIC
OCEANIC FISHES
• LANTERNFISHES (ELECTRONA,
GYMNOSCOPELUS)
• DEEP SEA SMELTS (BATHYLAGUS)
ANTARCTIC ENDEMICS
• LARGELY ORDER NOTOTHENIOIDEI
– ICEFISHES
– PLUNDERFISHES
– SPINY PLUNDERFISHES
– NOTOTHENS
• MOST IMPORTANT PELAGIC SPECIES:
PLEURAGRAMMA ANTARCTICUM
Pleuragramma facts
•
•
•
•
•
•
•
•
Length: 6 mm at hatching to 250 mm
Age 21 y for 245 mm fish
Age at sexual maturity est. 6-9 y (?!) (170)
Larvae first appear – Dec /Jan Terra Nova
0-1y in upper 50 m
1+ y fish in upper 200 m but below 50 m
2+ mainly below 200 m
Found exclusively on shelf
Pleuragramma antarcticum (n=684)
MOCNESS
Tucker trawls
absent
absent
1-5
1 - 10
6 - 10
10 - 18
Fish trawls
absent
1 - 20
21 - 100
101 - 363
Electrona antarctica (n=21)
MOCNESS
Tucker trawls
absent
absent
1-3
1-3
4-6
Fish trawls
absent
Table 1. Regional comparison of antarctic fish abundance and biomass integrated over the 0-500m and 0-1000m depth layers.
Site Marguerite Bay
season / year fall / 2001 & 2002
area: depth layer shelf: 0-500m
Ross Sea
Croker Passage
Marguerite Bay
Ross Sea
Weddell Sea
summer / 1999
fall / 1983
fall / 2001 & 2002
summer / 1999
fall / 1986
shelf: 0-500m
shelf: 0-500m
oceanic: 0-1000m
oceanic: 0-1000m
oceanic: 0-1000m
Species
#/m²
mg WM/m²
#/m²
mg WM/m²
#/m²
mg WM/m²
#/m²
mg WM/m²
#/m²
mg WM/m²
#/m²
mg WM/m²
Bathylagus antarcticus
0.002
8
---
---
---
---
0.041
275
0.086
276
0.150
2036
Cyclothone spp.*
0.001
<1
---
---
---
---
0.154
87
0.047
17
0.060
54
Electrona antarctica
0.057
367
---
---
0.114
898
0.239
946
0.140
246
0.170
835
Gymnoscopelus braueri
0.009
136
---
---
---
---
0.047
293
---
---
0.130
258
Notolepis coatsi
0.005
4
---
---
0.002
<1
0.033
31
0.073
46
0.510
44
Pleuragramma antarcticum
0.903
1079
0.532
585
0.034
397
0.004
5
0.027
33
---
---
Σ 0.977
1594
0.532
585
0.150
1295
0.518
1637
0.373
618
1.020
3227
* - includes C.microdon, C. k obayashii and unidentifiable specimens
BIOMASS COMPARISON UPPER 500 m
• Eastern Ross Sea Shelf: 585 mg WM/m2
• Marguerite Bay: 1594 mg WM/m2
• McMurdo Sound: 880 mg WM/m2
(Reisenbichler 1993)