Demersal Catch Abundance

Demersal Fish and Invertebrate Abundance and Distribution

Bob Lauth, Bob Foy, Mike Sigler, Brenda Norcross, Lyle Britt

Final Reports to CIAP and BOEM:

Britt, L.L, R.R. Lauth and B.L. Norcross. 2016. Paired catch comparisons from two standard bottom trawls used in Arctic surveys. US Dept. of the Interior, Bureau of Ocean Energy Management, Alaska OCS Region. OCS Study BOEM 2011-AK-11-08 a/b. 64 pp. – DRAFT REPORT

Abstract
Long-term monitoring of the high-Arctic marine biota is needed to understand how the ecosystem is changing in response to climate change, diminishing sea-ice, and increasing anthropogenic activity. Since 1959, bottom trawls (BT) have been a primary research tool for investigating fishes, crabs and other demersal macrofauna in the high-Arctic. However, sampling gears, methodologies, and the overall survey designs used have generally lacked consistency and/or have had limited spatial coverage. This has restricted the ability of scientists and managers to effectively use existing BT survey data for investigating historical trends and zoogeographic changes in high-Arctic marine populations. Two different BTs currently being used for surveying the high-Arctic are: 1) a small-mesh 3-m plumb-staff beam trawl (PSBT), and 2) a large-mesh 83-112 Eastern bottom trawl (EBT). A paired comparison study was conducted in 2012 to compare catch composition and the sampling characteristics of the two different trawl gears, and a size selectivity ratio statistic was used to investigate how the probability of fish and crab retention differs between the EBT and PBST. Obvious contrasting characteristics of the PSBT and EBT were mesh size, area-swept, tow speed, and vertical opening. The finer mesh and harder bottom-tending characteristics of the PSBT retained juvenile fishes and other smaller macroinvertebrates and it was also more efficient catching benthic infauna that were just below the surface. The EBT had a larger net opening with greater tow duration at a higher speed that covered a potentially wider range of benthic habitats during a single tow, and it was more efficient at capturing larger and more mobile organisms, as well as organisms that were further off bottom.

Goddard, P., Lauth, R., and Armistead, C., 2016. Results of the 2012 Chukchi Sea bottom trawl survey of bottomfishes, crabs, and other demersal macrofauna. US Dept. of the Interior, Bureau of Ocean Energy Management, Alaska OCS Region. OCS Study BOEM 2011-AK-11-08 a/b. 123 pp. – DRAFT REPORT

Abstract:
The results of the 2012 Chukchi Sea bottom trawl survey of bottomfishes, crabs, and other dermersal macrofauna are presented. The 2012 survey was only the fourth Chukchi Sea survey conducted by the National Marine Fisheries Service or its predecessor, the Bureau of Commercial Fisheries, since 1959. Seventy-one survey stations were successfully completed during the bottom trawl survey. The survey area extended north and east from the Bering Strait to Barrow Canyon, bounded to the west by the U.S.-Russia Maritime Boundary and east to the 10-m bathymetry limit along the Alaska coastline. Demersal populations were sampled by trawling at stations centered within 55.56 × 55.56 km (30 × 30 nautical miles) grid cells covering the survey area. Survey results presented in this report include biomass in metric tons (t), abundance numbers, and catch-per-unit-effort (CPUE; kg/ha and no./ha) for all taxa identified during the survey. Size composition and CPUE distribution plots are presented for the most abundant fish and invertebrate species. Appendices provide station data, summarized catch data by station, species listings, and biomass and population data for the sampled populations. Funding for this survey was provided in part by the Bureau of Ocean Energy Management (BOEM) Arctic Ecosystem Integrated Survey (Arctic Eis) contract agreement number M12PG00018.

Bottom Trawl 83-112 Summary

Figure 1. Catch Per Unit Effort (number/km^2) of Snow crab from the 2012 bottom trawl survey. Snow crab total catch weight of ~1,000 kg was tied with the fuzzy hermit crab for greatest among all crab species.

There are more maps located below and click the images to to enlarge!

Seventy-one of the 73 stations in the sampling design were successfully completed during the 2012 Chukchi Sea survey. Two stations were determined to be untrawlable. Station CH30-O01 was covered in ice, therefore no attempt was made to set the net. Two attempts to set the net were made at station CH30-N06, but due to excessive mud the station was abandoned.

Bottom depths ranged from 12 m at Station CH30-G04 in Ledyard Bay to 90 m at Station CH30-L08 along the northern boundary of the survey area at the edge of Barrow Canyon. Mean bottom depth for all stations was 42 m. Bottom temperatures ranged from -1.7 to 10.7 °C with a mean of 2.7°C. The warmest temperatures were in the shallowest waters along the coast with the exception of one station, CH30-B06, in Kotzebue Sound. The bottom temperature at this station was -0.4°C. It was the coldest temperature recorded south of Wainwright. Surface temperature ranged from -0.5 to 11.2 degrees Celsius with a mean of 5.2°C.

Total catch weight for the survey was 14,398 kg (14 metric tons). Total catch weights ranged from 7.7 – 1,660 kg with a mean of 202.8 kg (Table 2; Appendix A). Invertebrates accounted for 96% of the catch weight, while fish only accounted for 4%.

A total of 56 species of fish and 277 taxa of invertebrates were identified during the 2012 Chukchi Sea survey. Voucher specimens of fishes and invertebrates that could not be identified at sea were preserved and brought to Seattle for further identification. Invertebrate vouchers will be deposited at the California Academy of Sciences and fish vouchers at the University of Washington Fish Collection.

The CPUE distribution maps were created in collaboration with Distributed Biological Observatory and show major species catch CPUE in across the Arctic Eis survey region.

Figure 2. Catch Per Unit Effort (number/km^2) of Arctic Cod from the 2012 bottom trawl survey. Arctic Cod catch biomass (kg) from the 2012 bottom trawl was approximately 8x and 4x greater than the 2012 and 2013 surface trawls, respectively.

Figure 4. Catch Per Unit Effort (number/km^2) of Yellowfin Sole from the 2012 bottom trawl survey.

Figure 6. Catch Per Unit Effort (number/km^2) of Red King Crab from the 2012 bottom trawl survey.

Figure 3. Catch Per Unit Effort (number/km^2) of Saffron Cod from the 2012 bottom trawl survey. Saffron Cod catch biomass (kg) from the 2012 bottom trawl was approximately 4x and 20x greater than the 2012 and 2013 surface trawls, respectively.

Figure 5. Catch Per Unit Effort (number/km^2) of Green Sea Urchin from the 2012 bottom trawl survey. Urchin total catch weight of ~2,200 kg was the largest for any single species.

Figure 7. Catch Per Unit Effort (number/km^2) of Blue King Crab from the 2012 bottom trawl survey.

Other Final Reports

Final Report studies which include Bottom Trawl data:

  1. Gray B. G., Norcross, B. N., Beaudreau, A. H., Blanchard, A. L., and Seitz, A. C. 2016. Variability in the summer diet of juvenile polar cod (Boreogadus saida) in the northeastern Chukchi and western Beaufort Seas. US Dept. of the Interior, Bureau of Ocean Energy Management, Alaska OCS Region. OCS Study BOEM 2011-AK-11-08 a/b. 44 pp. – DRAFT REPORT
  2. Gray B. G., Norcross, B. N., Beaudreau, A. H., Blanchard, A. L., and Seitz, A. C. 2016. Food habits of Arctic staghorn sculpin (Gymnocanthus tricuspis) and shorthorn sculpin (Myoxocephalus scorpius) in the northeastern Chukchi and western Beaufort Seas. US Dept. of the Interior, Bureau of Ocean Energy Management, Alaska OCS Region. OCS Study BOEM 2011-AK-11-08 a/b. 57 pp. – DRAFT REPORT
  3. Helser, T. E., Colman, J. R., Anderl, D. M., Kastelle, C. R. 2016. Growth dynamics of Saffron cod (Eleginus gracilis) and Arctic cod (Boreogadus saida) in the Northern Bering and Chukchi Seas. US Dept. of the Interior, Bureau of Ocean Energy Management, Alaska OCS Region. OCS Study BOEM 2011-AK-11-08 a/b. 50 pp. – DRAFT REPORT
  4. Sigler, M. F., Mueter, F. J., Bluhm, B. A., Busby, M. S., Cokelet, E. D., Danielson, S. L., De Robertis, A., Eisner, L. B., Farley, E. V., Iken, K., Kuletz, K. J., Lauth, R. R., Logerwell, E. A., Pinchuk, A. I. 2016. Late summer open water zoogeography of the northern Bering and Chukchi seas. US Dept. of the Interior, Bureau of Ocean Energy Management, Alaska OCS Region. OCS Study BOEM 2011-AK-11-08 a/b.93 pp. – DRAFT REPORT
  5. Whitehouse, G.A., Aydin, K. 2016. Trophic structure of the eastern Chukchi Sea: An updated mass balance food web model. US Dept. of the Interior, Bureau of Ocean Energy Management, Alaska OCS Region. OCS Study BOEM 2011-AK-11-08 a/b. 149 pp. – DRAFT REPORT
  6. Whitehouse, G.A., Buckley, T.W., Danielson, S.L., Aydin, K. 2016. Demersal and pelagic fish food habits in the eastern Chukchi and northern Bering seas. US Dept. of the Interior, Bureau of Ocean Energy Management, Alaska OCS Region. OCS Study BOEM 2011-AK-11-08 a/b. 108 pp.- DRAFT REPORT

Manuscripts which include Bottom Trawl data:

    Lauth, R., Norcross, B., Britt, L., Kotwicki, S. in prep. Differences in catch composition and size selectivity between two bottom trawls used in Arctic surveys of bottom fishes, crabs and other demersal macrofauna.
    Divine, L. M., Iken, K., Bluhm, B. A. 2015. Regional benthic food web structure on the Alaska Beaufort Sea shelf. Marine Ecology Progress Series 531: 15-32.
    Divine, L. M., Bluhm, B. A., Mueter, F. J., Iken, K. in press. Diet analysis of Alaska Arctic snow crabs (Chionoecetes opilio) using stomach contents and δ13C and δ15N stable isotopes. Deep Sea Research Part II: Arctic Eis Special Issue.
    Gray B. G., Norcross, B. N., Beaudreau, A. H., Blanchard, A. L., and Seitz, A. C. 2015. Variability in the summer diets of juvenile polar cod (Boreogadus saida) in the northeastern Chukchi and western Beaufort Seas. Pol. Biol. DOI: 10.1007/s00300-015-1796-7
    Gray B. G., Norcross, B. N., Beaudreau, A. H., Blanchard, A. L., and Seitz, A. C. in review. Food habits of Arctic staghorn sculpin (Gymnocanthus tricuspis) and shorthorn sculpin (Myoxocephalus scorpius) in the northeastern Chukchi and western Beaufort Seas. Deep-Sea Research II: Arctic Eis Special Issue.
    Helser, T. E., Colman, J. R., Anderl, D. M., Kastelle, C. R. in press. Growth dynamics of Saffron cod (Eleginus gracilis) and Arctic cod (Boreogadus saida) in the Northern Bering and Chukchi Seas. Deep-Sea Research II: Arctic Eis Special Issue.
    Sigler, M. F., Mueter, F. J., Bluhm, B. A., Busby, M.S., Cokelet, E. D., Danielson, S. L., De Robertis, A., Eisner, L. B., Farley, E. V., Iken, K., Kuletz, K. J., Lauth, R. R., Logerwell, E. A., Pinchuk, A. I. in press. Late summer open water zoogeography of the northern Bering and Chukchi seas. Deep-Sea Research II: Arctic Eis Special Issue.
    Whitehouse, G.A., Aydin, K. 2016. Trophic structure of the eastern Chukchi Sea: An updated mass balance food web model. NOAA Technical Report AFSC.
    Whitehouse, G.A., Buckley, T.W., Danielson, S.L., Aydin, K. in press. Demersal and pelagic fish food habits in the eastern Chukchi and northern Bering seas. Deep-Sea Research II: Arctic Eis Special Issue.

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