THE MANX WHELK FISHERY PRACTICE, SCIENCE & MANAGEMENT
Jack Emmerson, MSc
School of Ocean Sciences Prifysgol Bangor University
Presentation to RINA & IMarEST, Isle of Man CONTENTS
• Fisheries Science – Bangor University & DEFA • Fishery Overview • Pre-existing knowledge of the species • 2015 / 2016 Scientific Projects • The life-history of ‘Manx’ population • Ongoing work • Aims for the future
Common whelk (Buccinum undatum)
Contents BANGOR UNIVERSITY & DEPARTMENT OF ENVIRONMENT, FOOD AND AGRICULTURE
Scientific evidence & advice to DEFA since 2007. 2 full-time staff on island. Manx Fishing Vessels DEFA HQ
Monitor the 5 most important shellfisheries: RV Prince Madog • King Scallop (Pecten maximus) • Queen Scallop (Aquipecten opercularis) • Edible crab (Cancer pagurus) • European lobster (Homarus gammarus) • Common whelk (Buccinum undatum)
Fisheries Science – Bangor & DEFA Fishery Overview ISLE OF MAN: FISHERIES OVERVIEW Value Stock Spatial (2016) Assessed Data
• King Scallop (Pecten maximus) £7.4 m
£2.2 m • Queen Scallop (Aquipecten opercularis)
£0.7 m • Common Whelk (Buccinum undatum)
£0.7 m • European Lobster (Homarus gammarus)
• Edible Crab (Cancer pagurus) £0.6 m
Fishery Overview WHELK FISHERY OVERVIEW
Whelk are targeted using baited pots by both medium (10 - 12m) and large (>15m) vessels.
Pots are baited with dogfish (S. canicula) and brown crab (C. pagurus) carcases.
Majority of catch is processed (cooked and de-shelled) on island, some live catch goes to UK for processing.
Main market for small whelk is France & east Asia. Korea is a growing market that prefers larger whelks.
Fishery Overview WHELK FISHERY OVERVIEW
Fishery Overview WHELK FISHERY OVERVIEW
Fishery Overview WHELK FISHERY OVERVIEW 2017/2018 licensing & management statistics:
Vessels with a IOM Whelk License: 20 (75% IOM Registered) Vessels permitted to fish within the inshore grounds (0-3 mile): 13 Vessels permitted to fish within the offshore grounds (3-12 mile): 17 Maximum number of pots in the 0-3 mile limit: 3,600 Maximum number of pots in the 3-12 mile limit: 15,600 Minimum Landing Size (MLS): 70 mm TSL Quota: None Days at Sea: None Closed Areas: None
Fishery Overview Pre-existing knowledge PRE-EXISITING KNOWLEDGE
• Manx whelk populations studied in the late ‘80s and early ‘90s. • Investigated the ‘energy budget’ of the species. • Explored ways to estimate density. • Determined growth rates using • Length-frequency analysis (mixed population) • Operculum analysis • Mark-recapture experiment. • Spawning cycles & reproductive biology.
Dr. Ahmert Kideys (PhD Liverpool University, Port Erin Marine Lab)
Pre-existing knowledge: ISLE OF MAN PRE-EXISITING KNOWLEDGE - DENSITIES • Pot sampling – density on average 0.2 m-2 • Decrease in density during peak temperatures….
• Mark-recapture method used to estimate densities. • 1,895 individuals released, at large for 250 days. • 34 recpatured (1.8%) – too low (value = 0.48 m-2)
• Underwater camera method = 0.33 m-2
Study Area: Douglas
Pre-existing knowledge: ISLE OF MAN PRE-EXISITING KNOWLEDGE - GROWTH
• Several methods used to explore growth (size-at-age). • Length Frequency Analysis (LFA) • Operculum Analysis (OA)
• Maximum size approx. 120 mm (TSL)
• Larger, faster growing whelks than NE England and N France.. Why?
• Growth parameters vary around the island.
Whelk operculum
Kideys, A. (1996) Helgoländer Meeresuntersuchungen. 50, pp 353-368
East Douglas growth parameters
Pre-existing knowledge: ISLE OF MAN PRE-EXISITING KNOWLEDGE – REPRODUCTIVE BIOLOGY
• Maturity is indicated by a sharp increase in the gonad weights (60-70 mm TSL)
• Size-at-maturity also indicated by penis size (70 mm) ♂ ♀
• Decrease in gonad index between Sept. and Feb. indicate egg-laying.
• Egg-laying potentially cued by a temperature regime.
• Hatching occurs 3-5 months after gonad release.
• Whelks > 80 mm contribute greatest supply of reproductive output.
Pre-existing knowledge: ISLE OF MAN PRE-EXISITING KNOWLEDGE – BANGOR EFF RESEARCH
• Variation over small spatial scales • Maturity • Population structure • Cause unknown - likely temperature & depth related. • Peak reproductive ‘activity’ in late summer and autumn. • Spawning (egg laying) in November. • Size-at-maturity of Welsh whelks between 51-76 mm TSL. • Whelks in shallower waters were mature at a smaller size. • Seasonality in maturity estimates • ‘Ideal’ time to assess reproductive biology..? • Site-dependent. Dr. Jodie Haig & EFF Staff
Pre-existing knowledge: WALES PRE-EXISITING KNOWLEDGE – BANGOR-CEFAS RESEARCH
Statolith
Operculum
Source: Dr P. Hollyman
Pre-existing knowledge: WALES Current Research
ISLE OF MAN RESEARCH BANGOR – ISLE OF MAN RESEARCH AIMS
• Re-evaluate biological parameters in light of recent fishery expansion • Size-at-maturity • Growth
• Densities
• Movement / connectivity
• Environmental ‘triggers’
• Improve monitoring (catches and effort)
ISLE OF MAN RESEARCH BANGOR – ISLE OF MAN RESEARCH METHODS
Fisher-dependent pot-samples Mark-recapture experiment (12-month programme, 2016) (Two summer experiments, 2015 & 2016)
• Covering all major fishing grounds. • Focussed research areas: • 2 samples per boat per month (~200 animals) • Ramsey Bay • Over an entire 12-month cycle • Proposed Offshore Wind Farm area • MSc student-projects (summer)
ISLE OF MAN RESEARCH BANGOR – ISLE OF MAN RESEARCH METHODS – POT SAMPLING
• Samples stored frozen when landed. • Catch data: soak time / bait / GPS / depth
• Thawed at a later date
• All animals underwent analysys • Shell size • Shell morphometrics • Sex • Total weight
• Subsamples underwent dissection (30) • Meat & Shell weight • Maturity status: Penis size (♂) – Ovary status (♀) • Shell damage • Samples retained for statolith analysis
2015/2016 Projects BANGOR – ISLE OF MAN RESEARCH METHODS – DISSECTION
2015/2016 Projects BANGOR – ISLE OF MAN RESEARCH METHODS – DISSECTION
2015/2016 Projects BANGOR – ISLE OF MAN RESEARCH METHODS
2015/2016 Projects BANGOR – ISLE OF MAN RESEARCH RESULTS
• A total of 6,049 Manx whelks analysed. • 2,338 were dissected
• Combined with Welsh whelk data • Total = 9,234 (3,290 dissected)
• Population structure varies around the island.
• On average, Isle of Man fishery targets larger whelk than in Wales.
• MLSIOM = 70 mm • MLSWALES = 45 mm
• Size – weight relationship significantly different: • Welsh whelks are heavier.. • Variation important for potential stock-assessments
2015/2016 Projects BANGOR – ISLE OF MAN RESEARCH RESULTS Peak = Ripening ovaries
Trough = Egg-laying
2015/2016 Projects BANGOR – ISLE OF MAN RESEARCH
RESULTS
2015/2016 Projects BANGOR – ISLE OF MAN RESEARCH RESULTS
2015/2016 Projects BANGOR – ISLE OF MAN RESEARCH RESULTS
ISLE OF MAN RESEARCH BANGOR – ISLE OF MAN RESEARCH LIFE-HISOTRY OVERVIEW
LIFE-HISTORY OF WHELKS IN IOM BANGOR – ISLE OF MAN RESEARCH TAGGING STUDIES
ADDITIONAL RESEARCH BANGOR – ISLE OF MAN RESEARCH TAGGING STUDIES
• Trial study in 2015 (Kideys methods) • Modified methods in 2016 • OWF area, 6-12 miles east of Maughold.
AIMS • Assess & estimate abundance (EIA) • Investigate movement (Biology) • Monitor population characteristics (Management) • Use Lincoln-Petersen index in mark-recapture experiment (novel) • Monitor catch statistics through several weeks of commercial activity
Matt Robsinon, 2015 Ed. Bolger, 2016
ADDITIONAL RESEARCH BANGOR – ISLE OF MAN RESEARCH TAGGING STUDIES METHODOLOGY – Lincoln-Peterson methodology for abundance
Step 1: Capture a subsample of a population Step 2: Mark this subsample (easily recognisable) Step 3: Release the marked individuals randomly back into the population. Allow time for the marked individuals to mix in with the rest of the population. 2 Step 4: Capture a second sample. 퐴 =Ń 휋푟 Use the ratio of marked:unmarked in the second capture to estimate abundance. 퐾푛 Ń = 푘 Ń = total number of animals (abundance) n = number of animals marked on first visit K = number of animals captured on second sample k = number of recaptured animals that were marked in second sample
ADDITIONAL RESEARCH BANGOR – ISLE OF MAN RESEARCH TAGGING STUDIES METHODOLOGY
3 x 1 km2 ‘study areas’ were established inside the OWF AfL
ADDITIONAL RESEARCH BANGOR – ISLE OF MAN RESEARCH TAGGING STUDIES RESULTS
3 x 1 km2 ‘study areas’ were established inside the OWF AfL
ADDITIONAL RESEARCH BANGOR – ISLE OF MAN RESEARCH TAGGING STUDIES RESULTS
Estimated3 x 1 km2 ‘study value areas’of OWF were AfL ~established £3.9 million inside the OWF AfL
ADDITIONAL RESEARCH BANGOR – ISLE OF MAN RESEARCH TAGGING STUDIES RESULTS Mean daily movement = 9.13 m
Ranged from 5.1 m to 10.7 m a day.
Greatest distance travelled was 815 m (228 hrs)
Very similar to SCUBA observations (8.3 m day-1) …… Very slow moving, suggesting low connectivity.
ADDITIONAL RESEARCH Ongoing Research BANGOR – ISLE OF MAN RESEARCH ONGOING BIOLOGICAL PARAMTER RESEARCH
• Validate the LFA growth analysis using statoliths.
ONGOING RESEARCH BANGOR – ISLE OF MAN RESEARCH ONGOING BIOLOGICAL PARAMTER RESEARCH
• Investigate Environmental cues in catch data
ONGOING RESEARCH - BANGOR – ISLE OF MAN RESEARCH ONGOING BIOLOGICAL PARAMTER RESEARCH
• Investigate Environmental cues in catch data
ONGOING RESEARCH Aims for the Future STOCK ASSESSMENT
Harvest Rate (HR)
Survey Abundance (CPUE)
Stock Health (Lmax5%)
AISM FOR THE FUTURE ADAPTIVE CO-MANAGEMENT “A sustainable, thriving and well-managed fishing industry providing high-quality seafood products, supported by respect for the marine environment” – Future Fisheries
AISM FOR THE FUTURE Thank you. [email protected]