Technical Briefing. Northern Cod (NAFO Div. 2J3KL) Newfoundland & Labrador March 23, 2018

Transcription

1 Technical Briefing Northern Cod (NAFO Div. 2J3KL) Newfoundland & Labrador March 23, 2018

2 Outline Purpose of this briefing Science advice & the precautionary approach Summary of stock status How we estimate stock size of Northern Cod Key factors Stock status Projections Advice Next steps 2

3 Purpose of this briefing On March DFO held its Canadian Science Advisory Secretariat (CSAS) regional peer review meeting on Northern Cod. This presentation will describe the results of the stock assessment and the advice provided to fisheries managers. What is CSAS? A national body that oversees the review and provision of science advice to inform DFO management decisions. Specifically, this group helps organize meetings where DFO scientists, biologists and others, including fish harvesters, university researchers, and other technical experts get together to review scientific information and help 3 inform how commercial fish stocks are managed.

4 Science advice & the precautionary approach The precautionary approach is a management framework used to determine catch limits and/or other management measures with the intention to: keep removals moderate when stocks are healthy; promote rebuilding when stocks are low; and, ensure low risk of harm to the stocks. DFO science identifies the limit reference point and provides an estimate of stock size in relation to the precautionary approach framework. Limit reference point: boundary between the critical and cautious zones, and represents the stock status below which serious harm is occurring to the stock. Fishing is to be kept to the lowest possible level below the LRP. Upper stock reference: boundary between the cautious and healthy zones, and represents a threshold below which catch must be progressively reduced in order 4 to avoid reaching the limit reference point.

5 Summary of stock status This stock has been showing improvement since 2012 but has declined from 2017 to The stock remains in the critical zone of the precautionary approach framework. Natural mortality rate has increased since A one-year projection shows a high probability of continued decline for A key determinant of the projected 2019 spawning stock biomass is natural mortality. So, how did we come to these findings? 5

6 HOW WE ESTIMATE STOCK SIZE The science behind our advice 6

7 Northern Cod areas Stock covers NAFO Divisions 2J3KL. Multispecies survey annual in fall and spring. Random sampling by depth across the stock area of Northern cod. 7

8 Multispecies survey Number, weight of cod at each tow. Also collect otoliths (age), maturity information, diet, etc. Forms annual index of abundance and biomass. 8

9 Fish per net Sentinel index data The index has declined in the last two years

10 Tagging Tagging indicates the overall exploitation rate is 8%. 10

11 11 KEY FACTORS

12 Fishery data Total reported landings in 2017 were 13,000t compared to 10,000t in Removals from recreational fishery are unknown. 12

13 Landings ('000 t) Landings ('000 t) Reported landings J 3K 3L 10 2J 3K 3L Year Year 13

14 Changing ecosystem Current assessments show a decline in capelin and shrimp (major food source of cod), and are likely to have an impact on cod. Climate information showed a warming trend to 2010 and then a decrease afterwards. 14

15 15 STOCK STATUS

16 How we monitor changes to the stock Spawning stock biomass (tonnes) is the weight of mature fish. Fishing mortality is measure of fishing pressure on the stock. Natural mortality is a measure of all other deaths excluding fishing such as starvation, old age, and eaten by other animals etc. 16

17 Northern Cod Assessment Model (NCAM) (Cadigan, 2016) Complex statistical model, which has been peer-reviewed by international experts. Integrates information on stock productivity. 17

18 SSB relative to LRP Overall status spawning stock biomass The Northern Cod stock declined from 2017 to 2018 and remains in the critical zone. The SSB has declined from 423 kt in 2017 to 315 kt in Cautious zone Critical zone Year 18

19 Numbers of age 2s (millions) A 1000 Stock status Year Year 19

20 Natural Mortality (M) Natural mortality The natural mortality rate has increased from 0.39 (70% survival) in 2016 to 0.74 (48% survival) in Year

21 Fishing Mortality (F) Natural Mo Fishing mortality Fishing mortality has increased from Year0.014 in 2015 to to in 2016 and in Year 21

22 Projections To 2019 only. Assumptions: recent biological conditions. range of catch. Projection of mature biomass to 2019 indicates a high probability of continued decline (i.e. low probability of growth). 22

23 23 ADVICE

24 Advice Consistency with the DFO decision-making framework incorporating the precautionary approach requires that removals from all sources must be kept at the lowest possible level until the stock clears the critical zone. 24

25 Next steps Stock assessment results will be posted to the CSAS website in the near future. Previous assessments are currently available. Fisheries management is consulting with industry in the coming weeks. The Science advice will be presented and discussed at these meetings. DFO senior regional officials will consider advice from DFO Science and input from industry in developing future Total Allowable Catch (TAC) and other management actions. Stock to be assessed annually. 25

26 Questions? 26