Fisheries-Independent Monitoring: Trophic ecology research

Transcription

1 Fisheries-Independent Monitoring: Trophic ecology research Kevin Thompson, PhD Fisheries Independent Monitoring Florida Fish and Wildlife Research Institute

2 Marine Fisheries Research at FWC Fisheries- Independent Monitoring Stock Assessment Fisheries- Dependent Monitoring Genetics Life History Population Dynamics

3 FWC-Fisheries Independent Monitoring Began in 1989 in response to stock reductions of Red Drum Expanded gears and labs through the 90 s FIM offshore component started in 2006 (Gag grouper) Expansion in last 5 years Multiple surveys and methods

4 Gut lab historical overview FIM s offshore presence increased in 2008 SEAMAP Cameras/hooked gear Current gut lab focus is offshore Filling in and updating ecosystem models-ewe and others Providing trophic data for biological summaries Answering specific ecological questions 3 full time and 1 part time staff working in gut lab positions

5 Methods Excise stomachs in field or in lab Stored in formalin for transport Rinsed, archived in vials with Isopropanol Samples analyzed based on criteria Current projects and papers Filling data known gaps Maintaining time series Upcoming mgmt. interest

6 Methods Gut cut in lab Fullness score given 0 (empty) to 5 (distended) qualitative scale Prey flagged as parasite, prey of prey, bait, or net feeding Prey sorted by taxa Coarse or fine scale Keys on remaining distinguishing features Counts given by minimum known organisms

7 Methods Volumetric estimation Displacement 4. Measure final volume Estimation by measurements Cylinder method Squash Elipsoid r V = πr 2 x h h h d slide h d slide sample coverslip (h = 0.1 mm) r V = 2 π h d 2 3

8 Variables Predator Prey Physical Species name Prey Number Reference Number Predator number Predator Number Collection Date Length Major Taxon Latitude and Longitude sex Family Sampling Type-in/off/cruise Fullness index Scientific Name Sampling Gear Suspect? Volume Depth Collection date Volume Method Salinity Analysis date Number Temperature Comments Parasite? Prey of Prey? Incidental? Habitat-varies by sampling type Total volume of stomach contents Volumetric measurements Reference number

9 Sample sizes >27,200 non-empties Of about 40,000 total (~20% total) 1597 number of prey species or taxa >90,000 predator-prey interactions Largest producer of trophic data in the GOM Predators Prey Species Occurrence Species Occurrence Gray snapper 2246 Actinopterygii 7334 Snook 1999 Crustacean, unknown 2700 Red drum 1790 Nematodes (parasite) 1902 Lane snapper 1743 Polychaeta 1497 Gag 1567 shrimp 1467 Largemouth bass 1506 Copepods 1217 Vermilion snapper 1244 Caridean shrimp 1000 Dusky flounder 1043 sediment 973 Rainwater killifish 997 Crab, unknown 911 Spotted seatrout 948 seagrass 897 Black sea bass 918 algae 800 Inshore lizardfish 771 shell fragment 767 Red grouper 763 Pinfish 754 Sand diver 574 swimming craps 736 Hogfish 555 Calanoida copepods 646

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11 Baitfish interactions Few baitfish stomachs in current database 30+ Threadfin Herring <10 Menhaden (Bre. smithi) Species level prey information limited Menhaden 7 occurrences Spanish Sardine 66 Threadfin Herring-41 Clupeidae Rank Predator 1 Red drum 2 Snook 3 Spotted seatrout 4 Spanish mackerel 5 Gray snapper 6 Gag 7 Inshore lizardfish 8 Red grouper 9 Vermilion snapper 10 Atlantic needlefish 11 Sand seatrout 12 Black sea bass 13 Sand diver 14 King mackerel 15 Lane snapper 16 Red snapper 17 Great barracuda 18 Gulf flounder 19 Snakefish 20 Atlantic sharpnose shark

12 Scientific contributions: modeling and databases EwE models of the West Florida Shelf Chagaris and Mahmoudi-FWC/UF Part of SEDAR process Updates for ecosystem model questions and assessments ATLANTIS models USF-Ainsworth GoMexSI Trophic database for the GOM Jim Simons Texas AnM

13 Scientific contributions: directed studies Utility of using jaws for identification of fish remains in stomach contents (in submission) The diet of opportunistically sampled Mola spp (Bull. of Mar. Sci. ) The diet of Hogfish on the WFS and in nearshore estuaries (data completed) Required new subsampling protocols

14 Shifts in spotted seatrout diet over time

15 All Taxa Copepods and mysids dominate size class 1 Ontogenetic shifts to more energeticallyrewarding prey Switch from copepods to mysids ~26 times more energy (Waggey et al., 2007)

16 Influence of Gag on distribution and diet of juvenile reef fish

17 Focal Species Black Seabass Centropristis striata Lane Snapper Lutjanus synagris Gray Snapper Lutjanus griseus Gag Mycteroperca microlepis Hogfish Lachnolaimus maximus White Grunt Haemulon plumierii

18 Potential Biotic Interactions Gag have recruitment pulses into southern estuaries Comparisons with high vs low recruitment years for Gag =High N Gag counts by year =Low CH TB

19 Abundances by Gag Year 600 Average annual abundance 500 Numbers Caught High Gag Low Gag Black Seabass Gray Snapper

20 Abundances by Gag Year 600 Average annual abundance 500 Numbers Caught High Gag Low Gag Black Seabass Gray Snapper

21 Abundances by Gag Year 600 Average annual abundance 500 Numbers Caught High Gag Low Gag Black Seabass Gray Snapper

22 Gag Diet Proportion N=461 Eugerres plumieri Syngnathidae Gerreidae Orthopristis chrysoptera Syngnathus sp. Paralichthyidae Stephanolepis Clupeidae hispidus Monacanthidae Bairdiella chrysoura Anchoa sp. other Farfantepenaeus duorarum Farfantepenaeus sp. Tozeuma carolinense Penaeidae Harengula jaguana Actinopterygii Lagodon rhomboides

23 Lutjanus NMS results p < gagyear 0 1 L. rhomboides Axis 2 Farfantepenaeus sp. Actinopterygii Caridea mixed seagrass Digenea Unident Hippolyte zostericola Crustacea Penaeidae Axis 1

24 Centropristis NMS results p < gagyear 0 1 Axis 2 Alpheoidea Brachyura Xanthoidea Actinopterygii seagrass Benthic amphipod mixed Decapoda Unident Caridea Nematoda Digenea Hippolyte zostericola Crustacea

25 Discussion Many uses for diet data Directed studies Ecosystem models and management Ecological studies Supports rigorous analyses with combining catch and diet datasets Patterns through ontogeny, space, time, and predator-predator interactions

26 Future directions and questions Molecular tools Genetics Isotopes Data gaps for large-bodied, deep reef fish Barotrauma Spearfishing? Influence on diet on other biological indicators within a predator Energy transfers Inshore to offshore via pinfish and other forage Seasonal shifts in diet Benthic biodiversity through time using common predators Benthic vs. pelagic pathways Emerging collaborations with PEW, IGFA, academic partners Forage fish dynamics