Survival of Discarded Trawl Caught Sole ( Solea solea) Peter Randall - - PowerPoint PPT Presentation

Survival of Discarded Trawl Caught Sole (Solea solea)

Peter Randall and Ana Riberio-Santos

11-16 November, 2017

International Flatfish Symposium Saint-Malo, France

World Class Science for the Marine and Freshwater Environment

Background

• The reformation of the Common Fisheries Policy on January 1st, 2014 introduced a phased landing obligation or

discard ban.

• Potential exemptions to the landing obligation including under the high discard survival provision

Article 15 paragraph 2(b) of the regulation allows for the possibility of exemptions from the landing

• bligation for species for which:

"scientific evidence demonstrates high survival rates, taking into account the characteristics of the gear, of the fishing practices and of the ecosystem”.

• The landing obligation requires all catches of

regulated commercial species on-board to be landed and counted against quota.

Reformation of the CFP

Estimating Survival

• Assessing the vitality (health status) of the sole.
• The Reflex Action Mortality Predictor (RAMP) approach was used.

This methodology relates reflex impairment to probability of mortality.

Vitality Assessment

Vitality Assessment - Injury Abrasion Scale Loss Fin Bruising

Estimating Survival

• Combining fish vitality scores with the likelihood of survival for each

vitality category to estimate a survival rate for the fishery.

• The Reflex Action Mortality Predictor (RAMP) approach was used.

This methodology relates reflex impairment to probability of mortality.

• Vitality assessment also based on four ordinal classes that are defined,

from very lively and responsive Excellent fish, through Good, Poor and unresponsive Dead individuals.

Vitality Assessment

Vitality Code Description ‘Excellent’ E Vigorous body movement; no or minora external injuries only ‘Good’ G Weak body movement; responds to touching; minora external injuries ‘Poor’ P No body movement but fish can move operculum; minora or majorb external injuries ‘Dead’ D No body or operculum movements (no response to touching)

a Minor injuries were defined as ‘minor bleeding, or minor tear of mouthparts or operculum (≤10% of the diameter), or moderate loss of scales (i.e. bare patch)’. b Major injuries were defined as ‘major bleeding, or major tear of mouthparts or operculum, or everted stomach, or bloated swim bladder’.

Description of the categories used to score the pre-discarding vitality of individual fish for the semi-quantitative activity method (from Benoît, et al., 2010).

Vitality Assessment

Estimating Survival

• Combining fish vitality scores with the likelihood of survival for each

vitality category to estimate a survival rate for the fishery.

• The Reflex Action Mortality Predictor (RAMP) approach was used.

This methodology relates reflex impairment to probability of mortality.

• Vitality assessment also based on four ordinal classes that are defined,

from very lively and responsive Excellent fish, through Good, Poor and unresponsive Dead individuals.

• This vitality estimate was combined with captive observation of

selected individual sole with different vitality scores to generate a weighted overall survival rate.

Vitality Assessment

Captive Monitoring

Captive Monitoring

Analytical Methods

• Captive observation data provide the period that each fish was
• bserved after capture and the state of the fish (dead or alive) at

the final observation.

• The Kaplan-Meier (K-M) estimator generates the survivor

function against time, for the observed period.

• Long-term survival predicted using a semi-parametric

proportional hazards mixture cure model (PHMC) & a parametric mixture distribution model (Wei) .

Survival

North Sea - IVc

No of Hauls Popn No of Sole Assessed No of Sole Captive Observn Period (hrs) SQA Proportion @ each vitality Obsvd Survival Extension model 1 (ph) Extension model 2 (Wei) 24 All Sole 1575 287 360 E 0.43 46% 42% 43% G 0.27 P 0.26 D 0.05 <24cm Sole 118 48 360 E 0.57 51% 47% 48% G 0.18 P 0.20 D 0.05

North Sea - IVc

North Sea EU LO Delegated Regulation Jan 2017

• 1. The exemption from the landing obligation pursuant to Article 15(4)(b) of Regulation (EU)

No 1380/2013, for species for which scientific evidence demonstrates high survival rates, shall apply in 2017 to catches of common sole below minimum conservation reference size made within six nautical miles of the coast in ICES area IVc and outside identified nursery areas with otter trawls (OTB) with cod end mesh size of 80-99mm.

• 2. The exemption referred to in paragraph 1 shall only apply to vessels with a maximum

length of 10 meters, a maximum engine power of 180 kW, when fishing in waters with a depth of 15 meters or less and with limited tow durations of no more than 1:30 hours.

• 3. Common sole caught in cases referred to in paragraph 1 shall be released immediately.

Conditional Exemption

Further evidence requested…

• 4. Before 1 May 2017, Member States having a direct management interest in the

North Sea shall submit to the Commission additional scientific information supporting the exemption laid down in paragraph 1. The Scientific, Technical and Economic Committee for Fisheries (STECF) shall assess that information before 1 September 2017.

Conditional Exemption

Solent- VIId

No of Hauls Popn No of Sole Assessed No of Sole Captive Observn Period (hrs) SQA Proportion @ each vitality Obsvd Survival Extension model 1 (ph) Extension model 2 (Wei) 25 All Sole 744 290 360 E 0.68 88% 79% 79% G 0.30 P 0.01 D 0.01 <24cm Sole 160 59 360 E 0.74 89% 82% 89% G 0.24 P 0.01 D 0.01

Solent- VIId

Evaluation of the landing obligation (STECF-17-08)

The 2017 Joint Recommendations (JR) proposes an exemption on the basis of high survivability for common sole caught by trawls with mesh size of 80-89 mm for ICES areas IV, and VIId. This exemption was first proposed in 2016 and the information provided on the fishery covered the North Sea and also for the English Channel. It was concluded that these were essentially the same fisheries and therefore combined the information from both JRs for its evaluation of the exemption request. In the 2017 request for this exemption, the scope has been extended to include fishing vessels of up to 221 kW power and those fishing at depths up to 30 meters. The main fishing gear to which this exemption shall apply are bottom otter trawls (EWG 16-10).

Confirmed Exemption

Conclusion

• The initial vitality and reflex impairment assessments of sole

showed good agreement with the mortality estimates, with those in better condition having a higher percentage of survival.

• Estimates exclude predation and may overestimate survival.
• Confident that visual vitality assessments of fish prior to

discarding are good predictors of mortality.

• The evidence generated from this work has already supported

EU legislation and is enabling an exemption from the Landing Obligation on the basis of high survival.

peter.randall@cefas.co.uk www.cefas.co.uk @CefasGovUK www.linkedin.com/company/cefas

peter.randall@cefas.co.uk www.cefas.co.uk @CefasGovUK www.linkedin.com/company/cefas