260 likes | 713 Vues
Recreational fisheries management. Issues and options. Recreational fisheries are IMPORTANT. According to NMFS, the total landed value of US commercial fisheries in 2009 was $2.29 billion (FAO says $31 billion, not clear why since doesn’t agree with tonnage reported to FAO)
E N D
Recreational fisheries management Issues and options
Recreational fisheries are IMPORTANT • According to NMFS, the total landed value of US commercial fisheries in 2009 was $2.29 billion (FAO says $31 billion, not clear why since doesn’t agree with tonnage reported to FAO) • US marine recreational fisheries were valued at of $12 billion, almost 1/3 Florida
Characteristics of recreational fisheries • Most often “open access”, no effort limitation • Very high economic value to small communities, rural areas (shift leisure spending from urban activities) • Typically take over from commercial fisheries when in competition (strong political voice, lots of voters) • Rarely cause biological overfishing (effort responds strongly to reduced abundance) • Create severe quantity-quality tradeoff problem
Vulnerability exchange process typically limits catch per effort Invulnerable fish vulnerable fish cpue Stupid, active, resident in places where gear works and access is best, typically <10% of total fish Smart, inactive, resident in safer places (eg deep)
Vulnerable density (cpue) Fishing effort CPUE typically very sensitive to fishing effort • CPUE often 5-10x higher at low efforts, because first increments in effort enjoy high catch rates, deplete vulnerable pool (foraging arena equation effect)
Fishing effort Total Fish Abundance Effort responses prevent increases in cpue • Typical response is nearly linear • Linear increase predicted if vulnerable density held roughly constant:c=co/(1+qE) E=1/q(co/c-1)(co=cpue at zero effort, c=cpue at equilibrium)
Approaches to recreational fisheries regulation • Size and bag limits (almost universal) • Seasonal closures (common) • Production side, hatcheries (common, do not increase cpue) • Spatial closures, MPAs (uncommon so far) • Limited entry--access management, license lotteries, etc. (very uncommon)
This will not be an objective presentation; my interest is in insuring that Junior and I can keep doing this
Growing recreational impact, even with restrictive bag and size limits, as for gag grouper in the Gulf of Mexico
Growing recreational impact often simply replaces commercial impact Book/Pompano.xls
So we are going to face progressively more severe restrictions as demand for both fishing and conservation grow • Open access fisheries lead to a syndrome of “success breeds failure”: effort expands until quality of fishing declines • There are two basic ways to restrict fishing mortality in open-access fisheries: • Reduce effective effort through bag limits, size limits, closed seasons • Spatial closures (protected areas) • Spatial and seasonal closures lead to concentration of fishing near closed area boundaries and at season openings
The quality-quantity tradeoff:Most of us end up getting screwed, most of the time Quantity (angling effort) Quality (cpue, size)
Most of us hate the very idea of spatial closures; I certainly do • But then I got to thinking about why I can still catch lots of spotted sea trout and red drum in my back yard in Cedar Key, Florida: most of the time, most of those fish are not in spots where people can catch them, i.e. the fish are in natual “marine protected areas” • And I started connecting that thinking with the stock assessment and modeling work that I do when I replace my fishing hat with my scientist hat (which thankfully isn’t too often anymore).
Mindless combination of size and bag limits can even cause worse conservation problems In this grouper example, green represents healthy recruitment levels, and red is severe overfishing. For low bag limits, increasing the size limit actually causes recruitment to decrease (move from green to yellow zone). Combining these regulations is kind of like taking Viagra and Valium at the same time: it might work, but…
Recent models for predicting redistribution of fish and fishing when areas are protected (MPAs) indicate that sustainable sport effort should often increase as closed area is increased Total sport fishing effort sustained Not enough fishing ground Not enough fish 0% Area closed to fishing 100%
EDOM model predictions of Gulf of Mexico red snapper fishing effort
For the red snapper example, MPAs might result in widely higher efforts, not just at MPA boundaries
Advantages Increased total yield when discard mortality is high Larger average fish size if used with size limits Increased cpue and number of fish kept Assures meeting Federal fishing mortality rate limits Disadvantages Effort concentration, competition Low cpue late in openings Encourages cheating (enforcement issue) A promising alternative: rotating closures (fallow rotation)
2008, 2012, … 2009, 2013, … 2010, 2014, … 2011, 2015, … Rotating closures for West Florida grouper management OPENINGS: Strips as shown are 0.1 degree (6 nm, 10 km) north-south; larger strips would be safer, but would more seriously limit local access to good grounds
Predicted gag grouper performance Annual total catch should remain high But catch per effort could be depressed
Quantity (angling effort) Quality (cpue, size) Even if we permanently solve conservation problems by using closed areas (MPAs, rotating openings), this problem will remain:Most of us end up getting screwed, most of the time
Should it be public policy that you only get what you pay for? • Attempts to improve quality in open-access public fisheries just result in increased fishing pressure, until quality declines to where it was. • The only way to stop this is to deliberately restrict effort. • One “fair” way to restrict effort is through a lottery system of some kind (like drawing permits for big game hunting).
So how do we keep the rest of you buggers out of my back yard? • Boat ramp quotas • Resident-only open areas (in my dreams) • Fishing club TURFS (like trout in Austria) • Misinformation to sports writers • Any other ideas???