Norton Sound red king crab can we look

Norton Sound red king crab: can we look at other RKC populations for information? Jenefer Bell Research Fishery Biologist Alaska Department of Fish and Game

Introduction Topics for discussion- • Trawl survey stratification and/or estimating abundance in untrawled stations • Male size at maturity • Disappearing large males

Trawl survey Triennial bottom trawl 1976 -2017 10 X 10 nm grid Core and Tier 1 stations became standardized in 1998 (Fair 1998) Tiers 2 and 3 were reported in 2002 trawl report (Brennan 2002) Abundance: area swept method

Trawl survey 1996 1999 2002 2006 2008 2011 2014 2017 47 (2014) to 86 (2008) stations in a survey it was assumed zero crab at untrawled stations

Trawl survey Annual bottom trawl survey 2018 - ? Redefined trawl area to include 60 stations X X Ø Ø Based on the tiers Crab presence Efficient trawl path Reasonable number of stations for weather windows Setting the stage for stratification methods…

Trawl survey Example stratifications temperature sediment type bathymetry Other suggestions or strategies? ? ?

Kodiak functional maturity (Powell et al. 2002) Kodiak size at 50% ovigerity (Pengilly et al. 2002) = Carapace length (mm) Observer data 2012 -2017; n = 1867 91 mm CL-m 71 mm CL-f Norton Sound size at 50% ovigerity (Paul et al. 1991) 1. 00 0. 90 0. 80 0. 70 0. 60 0. 50 0. 40 0. 30 0. 20 0. 10 0. 00 <56 57 59 61 63 65 67 69 71 73 75 77 79 81 83 85 87 89 91 93 95 102 mm CL-f Norton Sound functional maturity? Proportion 130 mm CL-m <56 57 59 61 63 65 67 69 71 73 75 77 79 81 83 85 87 89 91 93 95 Physiological maturity at 50 mm CL (Paul et al. 1991) Proportion Male size at ____maturity 1. 00 0. 90 0. 80 0. 70 0. 60 0. 50 0. 40 0. 30 0. 20 0. 10 0. 00 Carapace length (mm) Trawl survey 1996 -2017, n = 520 No Clutch

Male size at ______maturity 60 50 SL Legal Morphometric maturity Chelae height (mm) 40 30 n=202 (fall pot survey) 20 10 0 40 60 80 100 Carapace length (mm) 120 140 160 Other ideas about how to address male ______ maturity?

Disappearing large males 0. 45 0. 4 Comm Spring tag Fall pot Trawl survey Two options: 0. 35 Frequency 0. 3 Near shore in the summer 0. 25 0. 2 Migrate beyond the commercial fishery 0. 15 0. 1 0. 05 0 94 -103 104 -113 114 -123 Carapace length (mm) 124 -133 >134 Is this pattern apparent in other RKC fisheries? Where are large males commonly found?

Handling / Bycatch - Summer Commercial 35 30 SL L F CPUE 25 Concerns: Observed boats and sublegal densities • High abundance of sublegal crab in NS in 2012 -2015 skew results 20 15 10 5 0 2012 2013 2014 2015 2016 2017 2018 Handling in summer commercial fishery (based on observer program) Limited participation due to boat size and fishing locations • Representativeness of data

2017 T Har Sampled 50000 40000 30000 20000 10000 0 1200 1000 800 600 400 200 2015 50000 T Har 60000 50000 Sampled 40000 20000 10000 0 2018 T Har Sampled 40000 20000 10000 0 800 600 30000 400 200 800 30000 600 400 200 0 0 1000 Number of crab harvested 0 1000 2013 50000 T Har Sampled 40000 20000 10000 0 60000 2016 50000 T Har Sampled 40000 30000 20000 10000 0 800 30000 600 400 200 1000 800 600 400 200 0 Number of crab sampled 60000 Number of crab sampled 600 63 63 30 64 64 01 63 64 30 64 64 01 64 65 02 63 65 30 64 65 01 64 66 02 64 66 01 64 02 ot he r 60000 1400 63 0 62 64 63 01 63 63 30 64 64 01 63 64 30 64 64 01 64 65 02 63 65 30 64 65 01 64 66 02 64 66 01 64 02 ot he r 10000 01 20000 800 Number of crab harvested 30000 1000 Number of crab sampled 1200 Number of crab sampled 64 63 01 63 63 30 64 64 01 63 64 30 64 64 01 64 65 02 63 65 30 64 65 01 64 66 02 64 66 01 64 02 ot he r 62 Number of crab harvested 40000 T Har Sampled 64 Number of crab harvested 50000 62 0 2012 Number of crab sampled 0 64 64 01 63 64 30 64 64 01 64 65 02 63 65 30 64 65 01 64 66 02 64 66 01 64 02 ot he r 200 63 63 30 64 64 01 63 64 30 64 64 01 64 65 02 63 65 30 64 65 01 64 66 02 64 66 01 64 02 ot he r 10000 63 400 63 600 30 20000 01 800 63 60000 1000 63 Sampled 64 30000 62 T Har 01 70000 1200 64 40000 Number of crab harvested 2014 Number of crab sampled 50000 Number of crab sampled 64 63 01 63 63 30 64 64 01 63 64 30 64 64 01 64 65 02 63 65 30 64 65 01 64 66 02 64 66 01 64 02 ot he r 62 Number of crab harvested Handling / Bycatch 62 63 63 30 64 64 01 63 64 30 64 64 01 64 65 02 63 65 30 64 65 01 64 66 02 64 66 01 64 02 ot he r 63 01 64 62 Number of crab harvested 60000 1000 0 1400

Handling / Bycatch Is observer data useful to model? Yes – use crab lengths to calculate retention curves to estimate discarded crab Discards are important because they inform the abundance estimate for the next model year Suggestions for increasing observer participation? Maintain ‘large boat’ observers and have logbook-type collection from ‘small boats’

Any other thoughts on Norton Sound red king crab? ADF&G thanks subsistence and commercial crab fishermen for helping us collect information to help manage red king crab fisheries. ADF&G thanks Norton Sound Economic Development Corporation for their participation in and support of data collection projects to enhance management of red king crab fisheries.