rates of Alaskan shallow - water flatfish species Tom Hurst, - PowerPoint PPT Presentation

Temperature-dependent growth rates of Alaskan ‘shallow - water’ flatfish species Tom Hurst, Michele Ottmar, Cliff Ryer Fisheries Behavioral Ecology Program Alaska Fisheries Science Center NOAA-NMFS Newport, OR

Fla latfi fishes in in Ala laska • 24 Species recorded in Alaskan waters • ~ 15 species common in Gulf of Alaska and/or Bering Sea • 14 species commercially harvested • 2011 – 2015 average > 250,000 MT/y ~ $225 M/y • Most important species Yellowfin sole – largest landings of any flatfish in world Rock sole (northern + southern) – second largest landings Pacific halibut – most valuable – over $130 M/y commercial + important recreational + subsistence fisheries Compiled from: Mecklenburg et al. 2002. Fishes of Alaska NOAA Commercial fishery statistics website NMFS 2014. Fisheries economics of the United States

Sp Specie ies dis istrib ibutio ions – “shallow water complex” Northern rock sole Yellowfin sole Pacific halibut Alaska plaice English sole Longhead dab All six species reside in shallow coastal nurseries as juveniles. Adult distributions from Matarese et al. 2003 LHD distribution from Mecklenburg et al. 2002

Temperature-dependen dependent t growt owth h rat ates es. Temperature-dependent growth rates of juveniles Northern rock sole measured by Ryer, Hurst, & Boersma. 2012 0.03 Pacific halibut Specific growth rate 0.02 English sole 0.01 NRS PH ES 0.00 5 9 13 16 Temperature

Objectives: Measure temperature-dependent growth rates of Yellowfin sole Alaska plaice Longhead dab Compare thermal responses among 6 Alaskan flatfishes Contrast yellowfin sole and northern rock sole thermal sensitivity, habitat, distribution, and climate responses.

Fish ish coll llectio ions Collection locations: YFS: Kodiak, AK AKP: Nome, AK LHD: Nome, AK NRS: Kodiak, AK PH: Kodiak, AK ES: Newport, OR Fish collected from nearshore waters 3-20 m depth Otter trawl & beam trawl Held for several days at collection site Overnight shipment to AFSC laboratory on campus of OSU in Newport, OR

Exp xperim imental l facilit ilitie ies Because of logistical constraints associated with fish numbers and quarantine requirements for some species, we had to do experiments in two different sets of tanks. “small” rectangle tanks, n=32 “large” round tanks, n=15 Used for: YFS, AKP, PH Used for: NRS, PH, ES, LHD Crossover: LHD measured in tanks used for earlier studies Additional PH expt in small tanks at 9°C

Exp xperim imental l protocols ls Tank mean growth rates used in all analyses Number of independent tanks = 10-16 per species Fish acclimated to laboratory culture for at least 2 months prior use in experiments. Extended low temperature range to 2°C for AKP, YFS, LHD. Fish acclimated to test temperatures at approx. 1.5°C / day Acclimated for 2 weeks prior to measuring growth rates. Fish fed ad libitum once per day; “gel food” Measured 3-5 times at 2 week intervals Individual fish identified through size-rank differences except YFS & Supplemental PH experiment; RFID PIT tags in body cavity Analyses based on tank mean growth rates

Growth and su surviv ival Longhead dab Alaska plaice Yellowfin sole 100 100 100 0.015 0.015 0.015 Specific growth rate Specific growth rate Specific growth rate 80 80 80 Survival % Survival % Survival % 0.010 0.010 0.010 60 60 60 40 40 40 0.005 0.005 0.005 20 20 20 0.000 0.000 0.000 0 0 0 2 5 9 13 16 2 5 9 13 16 2 5 9 13 16 Temperature (°C) Temperature (°C) Temperature (°C) High survival to temperatures Survival declined above Low survival at temperatures where growth drops off. temperature of maximum above 10°C, but surviving fish growth. had high growth. *Not size-dependent.

Comparis Co ison growth th rates patterns across stu tudie ies Ryer et al. 2012. 0.03 AKP 0.015 YFS Specific growth rate Specific growth rate LHD 0.02 0.010 0.005 0.01 NRS PH ES 0.000 0.00 2 4 6 8 10 12 14 16 5 9 13 16 Temperature Temperature See generally similar patterns. Extended experiments to lower temperatures. Stronger effects observed at the highest temeratures.

Co Comparis ison growth th rates patterns across stu tudie ies??? AKP But overall slower growth observed YFS 0.03 LHD in AKP, YFS, LHD Specific growth rate NRS than NRS, PH, ES PH 0.02 ES Are there methodological 0.01 differences that can explain the lower rates observed in the current study. 0.00 2 4 6 8 10 12 14 16 Temperature

Hali libut exp xperim iment comparis ison An experiment on juvenile halibut conducted in 2016, at the same time as the YFS experiment allowed us to evaluate the potential for procedural differences between experiments. Growth at 9°C Ryer et al. 2012 Hurst and Planas, unpublished* 0.025 tested 5, 9, 13, 16° tested 2 and 9°C < 10% difference “large” round tanks “small” tanks in SGR 0.020 7 fish per tank 5 fish per tank not tagged internal RFID tags 0.015 mean 69.5 mm TL mean 66.7 mm TL 0.010 0.005 0.000 *Talk by Planas and Hurst, Tuesday 11am.

Size effects? Siz 0.040 Not enough size variation within each experiment to Maximum growth rate (SGR) 0.035 describe size-dependent variation in growth. PH 0.030 ES 16° NRS 16° But, likely not enough to be responsible for the observed 13° 0.025 differences in measured rates. 0.020 AKP YFS 13° 13° LHD 0.015 16° 0.010 40 50 60 70 80 90 100 Fish length (mm TL)

Siz Size effects? Age effects ts? 0.040 But, because of differences in the timing of spawning and settlement: Maximum growth rate (SGR) 0.035 Age 0 PH NRS, PH, ES were collected as age-0 0.030 ES 16° NRS 16° AKP, YFS, and YFS were collected as age-1 13° 0.025 Age 1 0.020 AKP YFS 13° 13° Similar patterns observed among juvenile gadids. LHD 0.015 16° 0.010 40 50 60 70 80 90 100 Fish length (mm TL) Is there an age effect on growth potential, independent of the general decline in SGR with increasing size. H 0 : age-0 (pre- first winter) fish are “different” than age -1 (post-first winter)? Laurel et al. 2016

Co Comparin ing temperature se sensit itiv ivit ity among sp specie ies Calculate temperature of maximum SGR LHD Representative? Calculate temperature range to 50% SGR High mortality at these temps. 12 Eurythermic ES 0.015 LHD 1.0 Relative growth rate Specific growth rate Delta T 50% SGR 10 0.8 0.010 NRS 0.6 8 PH 0.4 0.005 AKP 6 0.2 YFS Delta T Stenothermic 0.000 0.0 4 12 13 14 15 16 17 2 4 6 8 10 12 14 16 Temperature of maximum SGR Temperature (°C)

Im Impli licatio ions for r cli limate change The “Blob” – extensive area of warm waters Yellowfin sole may be most sensitive to climate change over the N. Pacific & Bering Sea because of their high thermal sensitivity. 12 ES LHD Delta T 50% SGR 10 NRS 8 PH AKP 6 YFS 4 12 13 14 15 16 17 Temperature of maximum SGR Already have field evidence of sensitivity.

In Interannual vari riatio ion in in growth refle lects thermal l se sensit itiv ivit ity Matta et al. 2010. MEPS. Collected NRS, AKP, and YFS from Bering Sea where the species distrubutions overlap. Look at synchrony and climate drivers of annual growth rates. Otolith ring width index based on within individual, across year variation.

12 Eurythermic ES LHD Delta T 50% SGR 10 NRS 8 PH AKP 6 YFS Stenothermic 4 12 13 14 15 16 17 Temperature of maximum SGR What about other parts of the distribution? Matta et al. 2010. MEPS.

Nort rthernmost range Northern rock sole General models would predict that warming would allow northern rock sole to expand farther north, occupying waters currently inhabited by YFS and AKP. But, coastal temperatures do not follow latitudinal trends. Yellowfin sole 100 0.015 Specific growth rate 80 Survival % X 0.010 60 40 0.005 20 0.000 0 2 5 9 13 16 Temperature (°C) Warming may reduce habitat suitability for the high latitude species even in the northern part of their range.

Su Summary ry Differences among species in thermal sensitivity. YFS have high thermal sensitivity and live in the most thermally variable environments. Growth responses did not match survival patterns in LHD. YFS will be more sensitive to climate changes. Climate change may alter habitat use throughout their range. Future: 1. Repeat experiments across ages to clarify size and age effects. 2. Perform temperature preference experiments – link performance to preference. 3. Spatially explicit model of seasonal growth potential. Broader: Explore how to integrate field and laboratory studies to improve understanding of climate and habitat interactions on fish distributions and productivity.