Size structure, distribution and interaction characteristics of dominant jellyfish from surface trawls in the Eastern Bering Sea Kristin Cieciel, Lisa Eisner, Mary Courtney, and Angela Feldmann Auke Bay Laboratory, Juneau, Alaska Picture by M. Courtney
Outline Sampling BASIS Collection methods Species encountered Size Structure Distribution Interactions & Associations Fish species Zooplankton Temperature and salinity Conclusions Future
Survey design and vessels US BASIS 22-2: 2: BASIS (Bering Aleutian Salmon International Survey) Commercial trawlers Mid-Aug to mid-oct
BASIS Sampling Components Surface Rope Trawl: Juvenile salmon, pelagic fish, jellyfish Surface trawl (m wide X 18m deep) Zooplankton Bongo net oblique tow (33 and μm) Juday net vertical tow (16 μm m mesh) Paravet-vertical vertical tow (1 μ m mesh) Oceanography Thermosalinograph (3m) CTD (Chl a, beam c, PAR, DO) Water samples (23-2) Microzooplankton Phytoplankton Chl a: >.7 μm m (GF/F), > 2 μm, > μm, > 1 μm m size Nutrients (N, P, Si)
U.S. BASIS Stations Number of Sampling Stations 24 = 143 2 = 127 26 = 18 Sampling is weather dependent Stations are 3 nautical miles apart Bristol Bay in late Aug to early Sept Saint Lawrence in late Sept to early Oct
Methods All jellyfish are caught in a surface trawl (~18m). Sorted by species, weighed, and measured for bell diameter. Diameter measurements are only made on intact individuals. Based on Suchman and Brodeur methods for trawl surveys.
Jellyfish typically caught in trawl Chrysaora melanaster Cyanea capillata Phacellophora camstichatica Staurophora mertensi Aurelia labiata Aequorea sp.
Bering Sea Jellyfish Biomass Index of large medusae biomass during the NMFS bottom trawl survey in the Bering Sea (PICES scientific report #28, 2) Biomass (1 t) 3 3 2 2 1 1 Bottom Trawl Surface Trawl 1982 1986 199 1994 1998 22 26 Year Data made available by Robert Lauth, AFSC, Bob.Lauth@noaa.gov
8 7 6 Distribution of Jellyfish catch on shelf 6 24 Total weight (t) 4 3 2 9 Total weight (t) Total weight (t) 1 8 7 6 4 3 2 1 8 7 6 4 3 2 1 Inner Middle Outer North of St. Lawrence Shelf Location 48 2 Inner Middle Outer North of St. Lawrence Shelf Location 47 64 26 Inner Middle Outer North of St. Lawrence Shelf Location 14 14 34 1 1
Frequency of Species Occurrence Frequency of Occurrence (%) Aequorea Aurelia Chrysaora Cyanea Staurophora Phaecellophora n 24 34 96 24 4 143 2 66 4 93 8 6 127 26 22 81 4 2 14 18
Species Composition by Location Aequorea Aurelia Cyanea Chrysaora Staurophora 1% 24 1% 2 1% 26 9% 9% 9% 8% 8% 8% 7% 7% 7% Total Catch (% ) 6% % 4% 6% % 4% 6% % 4% 3% 3% 3% 2% 2% 2% 1% 1% 1% % Inner Middle Outer North of St. Law rence Shelf Location % Inner Middle Outer North of St. Law rence Shelf Location % Inner Middle Outer North of St. Law rence Shelf Location
SIZE STRUCTURE
Aequorea sp. Oneway Analysis of Bell Diameter (mm) By Year 16 14 12 1 8 6 4 Inner Frequency 2 1 1 INNer Frequency 2 2 2 4 6 8 1 12 14 16 18 2 22 Middle Frequency 2 4 6 8 1 12 14 16 18 2 More Middle Frequency Bell Diameter (mm) 1 7 6 4 3 2 1 2 4 6 8 1 12 14 16 18 2 22 Out er Frequency 2 1 1 2 4 6 8 1 12 14 16 18 2 More Outer Frequency 7 2 6 1 4 1 3 24 2 26 2 1 2 4 6 8 1 12 14 16 18 2 22 2 4 6 8 1 12 14 16 18 2 22 Chrysaora melanaster Year Oneway Analysis of Bell Diameter (mm) By Year Bell Diameter (mm) 6 4 3 2 4 3 2 1 4 3 2 1 1 1 1 1 2 2 Inner Frequency 2 3 3 Middle Frequency 2 3 3 Outer Frequency 4 4 4 4 More More 2 18 16 14 12 1 8 6 4 2 2 18 16 14 12 1 8 6 4 2 1 1 1 1 2 2 INNer Frequency 2 3 3 Middle Frequency 2 3 3 Outer Frequency 4 4 4 4 More More 1 24 2 26 4 3 2 1 1 1 2 2 3 3 4 4 6 2 18 16 14 12 1 8 6 4 2 1 1 2 2 3 3 4 4 6 Year Oneway Analysis of Bell Diameter (mm) By Year Cyanea capillata 6 1 1 Inner Frequency 1 1 Inner Frequency Bell Diameter (mm) 4 3 2 1 1 1 1 2 2 3 3 4 4 6 Middle Frequency 1 1 1 1 2 2 3 3 4 4 Middle Frequency 1 1 1 1 2 2 3 3 4 4 Outer Frequency 1 1 1 2 2 3 3 4 4 Outer Frequency 24 2 26 1 1 Year 1 1 2 2 3 3 4 4 6 1 1 2 2 3 3 4 4 6
Interactions & Associations Picture by B. Stone
Trawl catches
Theragra chalcogramma Spirinchus thaleichthys Clupea pallasi Pleurogrammus monopterygius Trichodon trichodon Fish Species Ammodytes hexapterus Mallotus villosus
-178-174 -17-166 -162-18 -178-174 -17-166 -162-18 -178-174 -17-166 -162-18 Jellyfish 24 Biomass Distributions 24-26 2 26..4.4.3.3.2.2.1.1....4.4.3.3.2.2.1.1....4.4.3.3.2.2.1.1.. -178-174 -17-166 -162-18 -178-174 -17-166 -162-18 -178-174 -17-166 -162-18 Pollock 24 2 26. 4. 4. 3. 3. 2. 2. 1. 1.... 4. 4. 3. 3. 2. 2. 1. 1.... 4. 4. 3. 3. 2. 2. 1. 1...
Jellyfish 24 Biomass Distributions 24-26 2 26..4.4.3.3.2.2.1.1....4.4.3.3.2.2.1.1....4.4.3.3.2.2.1.1.. -178-174 -17-166 -162-18 -178-174 -17-166 -162-18 -178-174 -17-166 -162-18 Herring 24 2 26. 4. 4. 3. 3. 2. 2. 1. 1.... 4. 4. 3. 3. 2. 2. 1. 1.... 4. 4. 3. 3. 2. 2. 1. 1... -178-174 -17-166 -162-18 -178-174 -17-166 -162-18 -178-174 -17-166 -162-18
EBS24; Abundance (No m -3 ) Acartia longiremis; Bongo 33-178 -174-17 -166-162 -18 EBS24; Abundance (No m -3 ) Centropages abdominalis; Bongo 33-178 -174-17 -166-162 -18 EBS24; Abundance (No m -3 ) Pseudocalanus sp.; Bongo 33-178 -174-17 -166-162 -18 3 3 3 2 2 2 2 2 2 3 1 9 7 Large Medusae EBS 24, Biomass (g m -3 ) 3-178 -174-17 -166-162 -18-178 -174-17 -166-162 -18..4.4.3.3.2.2.1.1.. EBS24; Abundance (No m -3 ) Calanus marshallae; Bongo 1 1-178 -174-17 -166-162 -18 1 9 8 7 6 4 3 2 1 Small Copepods 24 Large Copepods EBS24; Abundance (No m -3 ) Metridia pacifica; Bongo 1 1-178 -174-17 -166-162 -18 1 9 8 7 6 4 3 2 1 EBS24; Abundance (No m -3 ) Eucalanus bungii; Bongo 1 1 1 9 8 7 6 4 3 2 1
Temperature at m (degree C) 18 16 14 12 1 8 6 4 2 Temperature and Salinity Data Total Gelatinous Catch (t) 1.9.8.7.624.2.426.3.2.1 24 2 26 2 4 6 8 1 12 14 16 Station Number 1 1 2 Temperature at m (celsius) Sallinity at m (PSU) 34 32 3 28 26 24 22 2 2 4 6 8 1 12 14 16 Station Number Total Gelatinous Catch (t) 1.9 24.8 2.7 26.6 24. 2.4 26.3.2.1 2 22 24 26 28 3 32 34 Salinity (PSU)
Conclusions Compared with previous years, 26 shows a notable decline in jellyfish biomass Bell diameters remained relatively the same for most abundant species, with the exception of Cyanea The relationship between most forage fish catches and jellyfish catches is unclear The middle shelf has the highest concentrations of jellyfish and lowest abundance of copepods Physical ocean factors seem to influence jellyfish distributions Fluctuations in biomass seem to be occurring at an earlier life stage that our survey does not observe
Future Research Continuation of sampling in 27 Analyze collected oceanographic data of past years Examine possible relationships between other fish species and jellyfish Explore density-depth relationship of jellyfish
Fin Acknowledgements Ocean Carrying Capacity Program Crews of the Sea Storm & North West Explorer Dr. S.K Shotwell, Dr. Bruce Wing, Cara Rodgveller, & Peter Hochstoeger