Impacts of the 2010 Cold Stun Event on N.C. Spotted Seatrout

N. C. Marine Fisheries Commission

New Bern

November 4, 2010

ISSUE

Periodic increases in mortality associated with cold stun events have a notable impact on the spotted seatrout population.

How was the N.C. spotted seatrout population

impacted by the 2010 cold stun event?

General Information

• Typically one kill per season• Impact depends on severity of the temperature

lows and rate of decline• Recovery time may be longer in the case of

consecutive events or unusual environmental conditions (hurricanes, floods)

• Life history traits (fast growth, early maturity, protracted spawning period) allow for relatively quick recovery

Cold Stun 2010

Cold Stun 2010

Population Size

0

1,000,000

2,000,000

3,000,000

4,000,000

5,000,000

6,000,000

7,000,000

8,000,000

Po

pu

lati

on

(Nu

mb

ers

)

Year

Recreational Lengths

4 6 8 10 12 14 16 18 20 22 24 26 28 30 32-4

1

6

11

16

A+B1n=10,025

Length Bin (TL, in)

Per

cen

t F

req

uen

cy

Recreational Lengths

4 6 8 10 12 14 16 18 20 22 24 26 28 30 320

10

20

30

40

B2n=11,502

Length Bin (TL in)

Per

cen

t F

req

uen

cy

Recreational Harvest

YEAR JAN/FEB MAR/APR MAY/JUN JUL/AUG SEP/OCT NOV/DEC2000 63,080 64,324 103,118 154,670 2001 2,125 44,279 15,366 75,122 76,546 2002 401 24,451 29,083 97,851 122,313 2003 5,803 33,913 24,310 12,075 69,837 2004 2,233 15,911 28,869 116,537 222,076 2005 1,470 3,891 38,506 16,876 131,403 436,592 2006 54,354 41,861 139,690 63,819 158,367 483,070 2007 9,755 9,861 50,219 168,149 94,890 655,650 2008 51,352 20,333 90,627 101,890 177,411 481,123 2009 19,879 41,909 267,469 113,837 85,781 304,693 2010 1,470 13,144 38,938 28,699

Commercial Lengths

7 8 9 101112131415161718192021222324252627282930310

2

4

6

8

10

12

14

n=131,551

Length Bin (TL, in)

Per

cen

t F

req

uen

cy

Commercial Harvest (lbs)

YEAR JAN/FEB MAR/APR MAY/JUN JUL/AUG SEP/OCT NOV/DEC2000 218,114 24,622 26,891 17,628 21,625 67,6932001 33,671 15,491 12,962 8,304 12,472 22,8152002 17,836 14,897 24,801 11,915 24,973 81,1342003 64,906 5,746 15,724 14,855 21,589 58,6422004 27,530 10,234 7,371 5,901 20,123 59,8022005 24,012 4,946 8,731 5,125 33,477 53,3102006 18,095 13,498 16,091 19,801 103,247 141,8872007 91,001 40,101 50,148 25,777 36,412 131,2832008 41,546 22,954 46,279 22,717 48,340 122,5942009 55,529 27,658 67,738 32,974 45,477 90,8702010 98,064 11,703 12,253 9,250

Monthly Commercial HarvestCold Stun Years

MONTH 1996 2000 2001 2003 20101 77,589 111,520 23,581 56,700 64,494 2 34,237 106,594 10,090 8,206 33,570 3 4,937 11,025 5,739 2,117 6,806 4 12,983 13,597 9,751 3,629 4,897 5 8,411 14,551 7,858 6,368 8,296 6 5,874 12,340 5,104 9,356 3,957 7 5,441 10,674 3,199 10,942 3,464 8 6,017 6,954 5,105 3,913 5,786 9 4,821 5,729 3,078 3,855

10 20,521 15,896 9,395 17,734 11 31,381 34,971 16,322 36,166 12 14,369 32,722 6,493 22,476

TOTAL 226,580 376,574 105,714 181,462 % Jan-Feb 49 58 32 36

Current Conditions

2003-2008 2010Landings 162,283 82,251

2009 2010Landings 443,094 82,251*Jan-Aug only; 29% of the recreational harvest

2003-2008 2010Landings 100,515 131,269

2009 2010Landings 183,899 131,269*Jan-Aug only; 42% of the commercial harvest

RECREATIONAL% Difference

-49% Difference

-81

COMMERCIAL% Difference

31% Difference

-29

Issue: Cold Stun Events

DMF SST AC MFC

• Give the sustainable harvest options the opportunity to work in rebuilding the stock to 20% SPR

• Status quo with the assumption that the director will intervene in the event of a catastrophic event and do what is necessary in terms of temporary closures by water body, but the director’s proclamation needs to be an informed decision based on quantifiable data and the outcome needs to be quantified post the closure

• Remain status quo with the assumption that the director will intervene in the event of a catastrophic event and do what is necessary in terms of temporary closures by waterbody

Potential Management Option 1

• Give the FMP recommended management measures (14-inch minimum size, 6-fish recreational bag limit, and commercial weekend closure) an opportunity to work in rebuilding the stock to 20% SPR so that SSB is large enough to recover more easily from cold stun events.

Potential Management Option 1

+ Population should recover faster, providing more fishing opportunities in shorter time span

+ Less likely the population will experience overfishing

+ Consistent management strategy

- More responsibilities for DMF Marine Patrol in terms of enforcement area and regulations

Potential Management Option 2

• Limit harvest through season closures (i.e., one month, several months, spawning season)

+ Partial decrease in the harvest mortality

- More responsibilities for DMF Marine Patrol in terms of enforcement area and regulations

- Difficult to quantify the amount of reduction

- Management strategy will change and may be difficult to inform public on temporary management measures

Potential Management Option 3

• Close the fishery immediately+ Total decrease in the harvest mortality

- Enforcement would be difficult and maybe

impossible

- Lost fishing opportunities for both commercial

and recreational fishermen

- Potential increase in the number of discards

- Difficult to quantify the amount of reduction

- Little information on the recovery of stock if

fishery dependent data are not available

Potential Management Option 1

• Give the FMP recommended management measures (14-inch minimum size, 6-fish recreational bag limit, and commercial weekend closure) an opportunity to work in rebuilding the stock to 20% SPR so that SSB is large enough to recover more easily from cold stun events.

COMMENTS/QUESTIONS?