Determining trips with effective effort for target species

1. Determining trips with effective effort for target species Melissa Monk and E.J. Dick April 22, 2013

2. Overview • Alternative method to Stephens-MacCall1 data filtering • Determine areas of “suitable habitat” • Structural zeroes vs observation zeroes • Data from onboard observer program for the Commericial Passenger Fishing Vessels (CPFV) • Drift-specific location data allows mapping of species-specific catches • Create buffered areas around positive-catch observations • Same method applied to Oregon/northern California and southern California • Variation of the method used for central California • Combining three datasets 1Stephens, A.E. and MacCall, A. (2004) A multispecies approach to subsettinglogbook data for purposes of estimating CPUE. Fisheries Research 70, 299–310.

3. Methods(Oregon/northern California and southern California) For each species • Map drift locations of positive species catch • Drift starting locations used for consistency • Create buffers around the points • Overlay drifts with zero catch and assign these drifts to a hull • Zero-catch drifts that don’t intersect with a hull are not used in the analysis

4. Map of all drifts Legend Positive-catch drift Zero-catch drift Possible location identifiers including axes, years, and species identification have been removed to ensure data confidentiality

5. 1. Map positive-catch drift locations Legend Positive-catch drift

6. Detailed Hulls (buffers) • Similar to a concave (alpha) hull • Detailed hull1 from XTools pro in ArcMap • Based on methods of Huff and Batsell (1977) • Buffer of 0.01 decimal degrees chosen • Buffer around a single point is 3.2km2 (1.25mi2) • Overlapping hulls were combined • Buffers clipped at the California coastline 1Huff, D.L. and R.R. Batsell. 1977. Delimiting the areal extent of market area. Journal of Marketing Research 14:581-585.

7. 2. Create buffers using positive-catch drifts Legend Positive-catch drift Zero-catch drift Hull

8. 3. Overlay zero-catch drifts onto buffers • Drifts within a buffer were retained for analyses • Area of each buffered region calculated Legend Positive-catch drift Zero-catch drift within hulls Zero-catch drift outside hull Hull

9. Application to indices • Apply data filter #1

10. Data filter #1 Trips and drifts meeting the following criteria were excluded from analyses: • Trips outside U.S. waters • Trips in which 70% or more of the observed catch composition was not bottomfish (CA only) Drifts meeting the following criteria were excluded from analyses: • Drifts deeper than 60 fathoms (CA) or 40 fathoms (OR) • Drifts in conservation areas, i.e. Cowcod Conservation Areas and MPAs, established prior to 2012 and prohibit the take of rockfish • Drifts in San Diego Harbor • Drifts missing both starting and ending location (latitude/longitude) • Drifts identified as having possible erroneous location or time data

11. Application to indices • Apply data filter #1 • Apply data filter #2

12. Data filter #2 Identify regions that were consistently productive for the target species Within a buffered area a species: • Must have been observed in at least 5 years • Must have been observed at least 5 times

13. Application to indices • Data filter #1 applied • Data filter #2 applied • Buffered areas were then aggregated to “super regions” in order to test YEAR:REGION interactions • The buffered areas were used as a factor in the GLMs • Relative areas were used to calculate area-weighted indices when the YEAR:REGION interaction in the GLM was significant

14. Area-weighted indices Copper rockfish (Southern region) China rockfish (Southern region)

15. Area-weighted indices Brown rockfish (Southern region) Copper rockfish (Northern region)

16. Central California Combined data three onboard CPFV observer programs (all surveys employed similar methods) • Historical database (1987-1998)1 • Made available by Deb Wilson-Vandenberg and Meisha Key (CDFW) • Primarily sampled San Luis Obispo County to Mendocino County • CalPoly database (2003-2011)2 • Samples San Luis Obispo County (port in Avila and Morro Bay) • CDFW current onboard observer program (1999-2011)3 • Samples the entire state (drifts from Cape Mendocino to Point Conception extracted) 1Reilly, P. N. et. al.[vars. eds. 1987-1995]. Onboard Sampling of the Rockfish CPFV Sampling Procedures and Lingcod Commercial Passenger Fishing Vessel Industry in Northern and Central California. California Department of Fish and Game, Marine Resources Administration Reports. 2Stephens, J., D. Wendt, D. Wilson-Vandenberg, J. Carroll, R. Nakamura, E. Nakada, S. Rienecke, and J. Wilson. 2006. Rockfish resources of the south central California coast: analysis of the resource from partyboat data, 1980–2005. CalCOFIReport 47. 3California Department of Fish and Game. 2011. California recreational fisheries survey methods. Prepared for Marine Recreational informatino program Review of California Recreational Fisheries Survey June 13-15, 2011, Los Alamitos, California.

17. Historical Database Sampling Methods (1978-1998) • Sampled 12 ports from Fort Bragg to port San Luis • “Trips selected on a random basis from a complete list of rockfish/lingcod CPFVs for each port area” • At each fishing stop, the sampler chose a reasonable number of eligible anglers to observe • Data collected • Starting and ending fishing times, starting and ending bottom depth • Starting coordinates Counts of all fish encountered by observed anglers

18. Current CDFW Sampling MethodsMarine Recreational Fisheries Statistics Surveys (MRFSS) (1999-2003)California Recreational Fisheries Survey (CRFS) (2004-present) • Stratified sampling program • Only most active CPFV landing sites included • Based on past distribution of effort • Data collected • Random subset of anglers chosen to observe • Drift starting and ending locations, times • All catch from observed anglers • Discarded fish lengths

19. CalPoly Sampling Methods(2003-present)

20. Central California • Historical database • Drifts within a trip aggregated to the level of site visit • Sites locations as defined in the database • Coordinates provided for each fishing site • CalPoly and current CDFW onboard programs include drift-specific locations • Starting locations used for consistency

21. Steps for defining effective effortCentral California • Thiessan polygons created for historical data • Each site location was used as the centroid • Map drift locations from CalPoly and CDFW onboard programs • Combined the databases for this analysis • Created buffers based on positive-catch locations • Intersect zero-catch drifts with buffered areas • Intersect buffered areas and Thiessan polygons to obtain “suitable habitat” within a polygon • Determine which historical sites to retain for analyses

22. Central California • Buffers were created using only the CalPoly and current CDFW drift-specific locations • Spatial resolution of the historical database at too coarse of a scale • Assuming that the current areas reflect “suitable” habitat • Highest resolution of spatial data

23. 1. Create Thiessan Polygons Legend Positive-catch location Zero-catch location Thiessan polygon

24. 2. Map CalPoly and current CDFW drift locations Legend Positive-catch location Zero-catch location Positive-catch drift Zero-catch drift Thiessan polygon

25. 2. Map only positive-catch drifts Legend Positive-catch drift Thiessan polygon

26. 3. Create buffers(using only CalPoly and current CDFW drifts) Legend Positive-catch drift Thiessan polygon Hull

27. 4. Intersect zero-catch drifts with hulls Legend Positive-catch location Zero-catch location Positive-catch drift Zero-catch drift within hull Zero-catch drift outside hull Thiessan polygon Hull

28. 5. Intersect buffered areas with Thiessan polygons(calculate area of “suitable” habitat within a polygon) Legend Positive-catch location Zero-catch location Positive-catch drift Zero-catch drift within hull Zero-catch drift outside hull Thiessan polygon Hull

29. 6. Determine historical sites to retain(historical sites intersecting area of “suitable habitat”) Legend Positive-catch location Retained zero-catch location Removed zero-catch location Thiessan polygon (sites retained) Thiessan polygon (sites removed) Hull

30. Application to indices • The hulls (regions) were used as a factor in the GLMs • Areas were aggregated after all data filters combined to increase sample sizes • Proportional areas of hulls were used when the YEAR:REGION interaction in the GLM was significant • Area-weighted index calculated

31. Sensitivity – using a larger buffer 0.03 decimal degrees Legend Positive-catch drift Zero-catch drift Hull

32. Buffer Comparison Buffer = 0.01 degrees Buffer = 0.03 degrees Legend Positive-catch drift Zero-catch drift Hull Zero-catch drift

33. Main Effects Model Index (with 0.03 buffer) • The same data filtering methods were used as for all other indices • Started with 33 regions • Sixteen regions remained after filtering • Collapsed to the same 3 super regions as used in the assessment index (North of San Pedro, Islands north of San Pedro, and South of San Pedro)

34. Area-weighted Index (with 0.03 buffer) • Binomial GLM had a significant YEAR: REGION interaction

35. Index Comparison

37. Comparing Indices: CDFW Onboard Observer and the NWFSC Hook and Line Survey • Comparison made for Vermilion rockfish in the Southern Area (south of Pt. Conception) • Sunset rockfish are not recorded in the CDFW onboard program • Identified drifts from the CDFW onboard program that overlapped with Hook & Line Survey fixed sites • Drifts within ≤ 2km of a Hook &Line survey fixed site were retained • Represents 71 of 121 Hook & Line Survey sites • Using the retained drifts, the methods for determining trips with effective effort applied

38. Index Comparison

39. Questions?