December 3, Fisheries & Marine Reserves. 1. Problems with fisheries. 2. Video on fisheries in New England. 3. Marine reserves - pros and cons. 4. Data on marine reserves.

Problem #1: More & more fisheries are collapsing (>90% decline) or going extinct (100% decline). % taxa extinct % taxa collapsed A higher proportion of fisheries collapse in areas with low species richness. Worm et al Science.

cumulative collapses per year Same story - more and more fisheries are collapsing.

Problem #2: Top layers of ocean are heavily fished. Fishermen are going into deeper and deeper waters. More and more taxa being exploited What does “20/20” represent?

Predictions Made By Fisheries Scientists were VERY Wrong for cod. Problem #3: There is little evidence that we can “manage” natural populations.

Video on Fishing Issues for New England.

Need pre-cautionary, risk-averse policies. -Don’t let your fish stocks crash. Need to manage the behavior of the humans. Recent push for marine reserves. 20% by 2020!

1. Make a list of the benefits (and costs) of marine reserves. 2. What are our goals for marine reserves? What do we want them to do? What criteria will we use to determine whether they are beneficial?

Marine Reserves are Gaining Popularity

Marine reserves effect age-structure of the population. Minimum Size RestrictionsMarine Reserves

Trawlers Catch a lot of fish Bottom trawls damage the benthic environment Marine reserves protect the physical nature of ocean floor.

Trawlers Damage Bottom Habitats that Fish Depend Upon. Sea Corals and large algae are destroyed.

By-Catch From a Trawl. Marine reserves may be beneficial for both target & non-target species.

National Marine Fisheries Observer Programhttp:// halibut as by-catch Jeff with a skate. Salmon is by-catch laying in the tub.

Of total world fish catch – 4 to 5% is by recreational fishing. If you exclude Pollock & menhaden (which are not fished by recreational fishing) – the number goes up to 10%. Among species of special concern – 25% of fish catch is by recreational fishing. Marine reserves will also limit mortality due to recreational fishing.

Gulf of MexicoSouthern Atlantic Pacific Coast North East Commercial Vs. Recreational Effects of Fishing. Take-home message - Recreational Fishing also increases fish mortality for species of special concern. Marine reserves will also limit mortality due to recreational fishing.

Black Grouper in a reserve Snappers in a reserve

Early Evidence Suggests that Reserves do increase Biomass in Adjacent Areas

As populations accrue larger individuals, egg production at the population level goes up. This can lead to spillover effects. However, this takes time. average annual eggs spawned (millions) Scallop Age (years) More spillover effects.

Most recent analyses suggest that marine reserves work in increasing diversity, CPUE, catch, ecosystem function, and tourism. Meta-analysis of studies on marine reserves. Black dots - unweighted averages. Open dots - weighted averages (by sample sizes). Worm et al

Last Set of Questions Which species will benefit most from marine reserves? Which fisheries will benefit most from marine reserves? Which species will see less benefit from marine reserves?

Review Questions. 1. What three observations have led people to seek a “risk-averse” management strategy in marine reserves? 2. List 5 ways that fisheries are damaging to fish populations. In theory, how would marine reserves effect this? 3. List 3 ways that fisheries damage wild populations with non-intended takes. How much of fishery mortality is estimated to be a consequence of by-catch? 4. What are our goals for marine reserves? What evidence is there that marine reserves increase #s and biodiversity within the reserves? What evidence is there are spillover effects? 5. List 4 different criteria for determining whether or not marine reserves are “beneficial”. Which criteria do you think are likely to be upheld and which ones are likely to not be true? 6. Can marine reserves result in a global λ > 1 for a species that is the target of harvesting? What would have to be done to have λ > 1? 7. In your opinion, are marine reserves a good idea? 8. What types of species are most likely to benefit from marine reserves? 9. Where should marine reserves be located? How large should they be?