Week 6-12 Fisheries PDF

Week 6-12 Fisheries Most under-reported sector   For WA - Boat-based and some shore-based for nation wide collection - Issue: data collection different in between states   BUT!   Finland and USA has recreational fishing data (long-term)   USA - Started in 1955: national survey of f...

Week 6-12 Fisheries Most under-reported sector   For WA - Boat-based and some shore-based for nation wide collection - Issue: data collection different in between states   BUT!   Finland and USA has recreational fishing data (long-term)   USA - Started in 1955: national survey of fishing, hunting and wildlife associated recreation - Every 5-10 years - More a economy survey than fish population - Three types of fishing: Freshwater, great lakes, saltwater - Collect information about anglers, hunters and wildlife watcher - No information about catch - A different survey: Salt-water angling survey - First national estimates of total recreational catch by species, region and method of fishing over the previous 12 months - Found in the first - 1.4 billions pounds (639.997 t) - 228 pounds per year per fisher - Overestimated by 200-300%. - Concluded that fishers should not be required to recall fishing trips that occurred more than two months in the past - Redid the survey in 1981 - Telephone surveys - Intercept surveys - Catch divided into two categories - Retained - Discarded - Did different survey for tunas and charter boats Finland - Recreational fishing is only 10% of the industrial - FAO was not aware that Finland also included recreational data in their total so did not note it. - Taxa dominated by pike, carp and trout (these are freshwater species??) - Very low salinity in the Baltic Sea due to limited access to large open ocean   Bahamas - Recreational fishing 55% of catch - Large decline in 1980 due to introduction of catch limits   Australia - Recreational fishing is popular pastime for Australians - Historically no studies done prior to 1970s - First one was done 1984 - Fishers assumed that catches were lower than commercial fishing - Depending on where you look, recreational fishing can be much higher - One challenge: fishing data is management by states making it hard to get all data combined because it is often gathered differently - Dirk is happy to life with uncertainty (little data is better than non)     **Global Recreational catch** - Estimated catches from 1950-2014 - Based on independent reconstructions for 125 countries - Marine recreational fishing accounts for less than 1% of total global marine catches - Catch and release is not accounted for (expect for USA) - The post release mortality rate is very high     **Recreational shark fishing in Australia** - More species are more robust but taking it out of the water will drastically increase the mortality rate - Sharks do not have skeletons - Conservation impactions of land-based trophy shark fishing Recreational fishing lecture: Objectives and management   5 times more recreational fisher than commercial fishers   West Australia - 25% of the populations is recreational fishers - People who fish once a year so take it lightly - \$2.4 billion expenditures (compared to Australia commercial fishing is much less)   How do we get data? - Bi-annual phone diary (3000 fishers) - Boat ramps surveys (3000 fishers) - Boat ramp cameras   Topics - Shark depredation - Higher closer to boat ramps - Localised depletion - Close to population - Recreational fishers tend to be very localised - No-take marine reserves     The objectives of recreational fishers are not the same as for commercial fishers In general, more about fishing experience with a variety of contributing factors       Management levers - Commercial : Catch quota and effort quota - Recreational: Bag limits, size limits and seasonal closures - When fishing participation increases so does catch     We can study fishers behavoiurs to udnerstand waht is imporant in fishing trips In WA access (SEE SLIDE) WA stock assessment Tuesday, 17 September 2024 10.02 Main data in WA: - Catch - SPUE datas (catch rate)       UN Convection on Law of the Sea (1982)   Supporting science based decision making - Ecosystem based management (EBM) - Ecosystem based fisheries management (EBFM) - Single fishery management   What is stock assessment - Stock assessment involves the use of various statistical and mathmetical calculations to make quantitative perdition about the reactions of fish populations to alternative management choices - Hilborn and walters (1992) - So how is fish populations changes through time - Decrease or increase -\> what is the response? Harvest strategy - Formal document including - Objectives = what are we trying to achieve and why - Performance indicators and reference points = adult Biomass and fishing mortality or exploitation and fishing pressure (often females are the limiting factor) - Monitoring and assessment strategy = data collecting, methods, analysis needed to estimate performance indicators - Harvest decision rules = so what are you going to do based on the results?   BMSY = Biomass maximum sustainable yield - High mortality early larval stage   Overfishing: high fishing mortality rate and high spawning biomass Overfished: High mortality and low spawning biomass   Resource allocation - Who gets the resources? Recreational or commercial?   Risked based approach - Minor = biomass \> target - Moderate = biomass between threshold and target - High = biomass between ??? See slide - Major = above limit AND - Remote (\ often fishing boats are not malleable capital) Subsidised - Bad for the stock - Really bad for effort (effort grows, more fish getting fished) - Bad for policy (but good for politicians)   Three categories of subsidies - Harmful or capacity-enhancing subsidies (Bad) - Increase fishing effort - Encourage fishers - Beneficial (good) - Led to more sustainability - Ambiguous (ugly)   MEY = Maximum economic yield = maximise profit not catch - Higher net profit often is found with effort lower than the MSY (Maximum sustainable yield) - MEY is generally around 60-70% of MSY     High seas fishing sat the current scale is enabled by large government subsides and substantial labour cost cutting, without which as much as 54%   Summery - Ex-vessel prices (direct return to fishers) - Cost of fishing - MEY - Subsidies - Labour (modern slavery) Data-limited stock assessment options Tuesday, 24 September 2024 15.03 In Europe: - 400 exploited stocks but only 100 have sufficient data for traditional age-structured stock assessment - WA also same issue - Developing countries virtually no data   **Rainer Froese** - Came up with simpler approach to get some stock assessment for especially developing countries   **BSM:** Bayesian Schafer Model - Should be bove 50% to be a heathy biomass for a fish populations - Estimated stock status (B) and exploitation (F) from reliable catch and abundance data (CPUE) - Advantages: can utilize short and interupted time series of abundance (CPUE) - Can estimate catchability q - Gives desired fisheries reference points MSY, B(msy) and F(msy) - Give egological reference point r(max) and k - Gives stock size as B and status as B/B(msy) - Give... (SEE LECTURE SLIDE) - If your B(msy) is 0 then your data is spot on     **CMSY:** Catch maximum sustainable yield - Estimates stock status (B) and exploitation from reliable catch data and estimates of species-specific resilience (r - populations growth rate) - Needs priors for resilience *r* - Qualitive resilience and their r ranges are available for all species - Very low= 0.015-0.1 - Low= 0.05-0.5 - Medium= 0.2-0.8 - High = 0.6-1.5 **AMSY:** Abundance maximum substantiable yield - Estimates stock status (B) and exploitation from reliable catch data and resilience but available catch data are unreliable or if true stock boundaries are unknown - Catch-per-unit-of-effort (CPUE) data quite common at useful levels for assessment - For this case you do not need to convert to a standardized unit ( kg per h ect.) - Not need as long as you are consistent - Remember to account for catchability = some species may have high when others have low - This method - Reasonable uncertainty around B/B(msy) - Suitable for management advice - High uncertainty around F/F(msy) **LBB:** Length-based Bayesian Biomass - Allows for a proxy for the relative biomass capable of producing maximum and sustainable yield - LBB reproduced the \"true\" parameter values of the simulations - Only 18% of all the assessed population deemed healthy in terms of biomass status - 82% are not   Critique; too unreliable. But yes ofc (according to DIRK) it makes sense, but if it is the only thing available then it will do. Better a little data than no data   SEE LAST SLIDE (CONCLUSION) FOR A CLEAR COMPARISON   **Bayesian statistics:**\ - we have some prior knowledge (prior belief), and then we collect some data and then we challenge the preexisting knowledge with the data to create a new state of knowledge (new evidence) - parameters: r = rmax and k are estimated from = (SEE LECTURE SLIDE FOR FORMULA) - Need priors to intrinsic rate of population increase r(max) (also called resilience) - R(max prior can sometimes be found in FIshBase or SeaLifeBase - But uncertainty but better than nothing History in Fisheries Science Tuesday, 1 October 2024 10.05 - Benefits of a long-term perspective on oceans and seas   History means: deals with much more broad perspective (past but extends far beyond our memory)   **Shifting Baseline Syndrome** - Defined by Daniel Pauly in 1995 - Taking stock: Overfishing since 1050 - Pauly also wrote a paper \"Fishing down marine food web\" Science 279, p. 860 - Drawing attention to global over-fishing in \"Counting the last fish\" - Understanding human impacts on extended timescales   Histroy of marine animal populations   Why should fisheries work with historians? - Essential for establising reference points for assesing stocks - Virgin stock - initial biomass Freshwater and inland fisheries Tuesday, 1 October 2024 11.03 - Data quality is worse in inland fisheries compared to marine? - Commercia fisheries all small-scale (no industrial fisheries with 2-3 expectations) - Where do industrial freshwaters fisheries exist? - great lakes - Used to have commercial but slowed down - Large rivers - Capsian Sea (Above Iran and below russia) - No water outflow - Evaporation loss - Historically productive waters - Sturgeon (caviar) - Endemic anchovy/herring - Fisheries in the \"sea\" - Small scale but commercial fisheries - Used to have industrial fisheries and are starting to develop again - Only a small number - Very large recreational sector - Aral sea - In Kazakhstan - Shrank in 1960s and by 2010 is had nearly dried up - Used to be the 4th largest lake in the world - Recreational fisheries increasing dominate freshwater fisheries - Largely unreported   While reported catch volumes are low, underreporting likely higher than marine systems - Lake Volta (Ghana) - 1996 reported: 75000 t - 1996 estimated: 150.00-200.000t - 2-2.6 times higher Thai freswater cathces - 5 times higher than reported   Mekong detla cpuntries - Reported 1.6MT - Lower reaches 2.6MT   **Freshwater fisheries data** - CSIRO journal and reviewers - Wide open field Freshwater fisheries (Kenya) Tuesday, 1 October 2024 15.00 Dr. Wanja Nyingi   Kenya Freshwater - Lower to middle income country - Rapidly growing population - Food and nutritional security concerns - Mal nutrition and micronutrient deficiencies - 90% of the country is freshwater fisheries - Lake Victoria is the 2th largest lake in the world - Kenya owns 6% of the lake - Historically dominated by extremely high diversity \>350 spp. Of endemic cichlids - Very popular aquaria species - Supported ancient, sustainable fisheries - In 1954 deliberate introduction of the nile perch and nile tilipa - Wanted to provide bigger fish for fishers - Until 1970 = 80% was cichilds and 20% introduced species - By late 1980, \>80% of fish biomass was Nile Perch - Over 1/2 of endemic species were?? - Traditionally chichilds where dried in the sun to preserved - But the introduced species where too big and had to be either smoked or feezed - This led to deforestation due to demand for firewood - This further led to harmful runoff to the lake - Much catch and employment BUT not much for the local population - Reconstruction of Data - 32% was not reported - 92% of that was from the lake Victoria - Miss reporting was underestimated from Kenya - Aquaculture data was getting into the data - Freshwater catch - Lake Turkana dominates the catch but.. - Mid 1970s driven by large fisheries infrastructure investment - Why underreporting? - Artisanal 80% driven by commercial Lake Victoria fishery - 91% reported - 20% subsistence - 71% unreported     - Flood-dependent ecosystems - Requires to be wet all the time (flooded) - Farming, fisheries and cattle - Impacts of dams on the Tana River Delta - Haf major impacts on the flood dependent ecosystems in a negative way - Mangroves along the delta and coast are important fish breeding sites   Climate change and fisheries Tuesday, 15 October 2024 10.01 Climate change - Happening much faster than generally projected - Caused by humans - 2015 Paris agreement: keep well below 2 degreess and aim for 1.5 degrees   Global bank 2012 speech aboyt climate change = everything is true   Arctic fires and warming: thawing the permafrost - potential to release the worlds largest deposit of methane (25x more than Co2) = positive feedback loop - Thermokarst depression - a kind of sinkhole or \"mega slump\" driven by the collaps and fracturing of the ???   Un-extraced fossile fuels in a 1.5 degree world (8 september 2021)   Impacts of climate change - Increase average water temperature - Not all are heating up (and not equally) - Most coastal warming is cooling - Some pelagic cooling - Change in oxygen content - Acidification - Sea level rise - Changes in ocean current regimes   **Ocean temperature and change in species distibution**   Most extinctions are around equator Most invasions are in temperate and high latitudiale areas   Change in max. Catch potential from (SEE SLIDE)     Less fish in the tropics - more in the cooler temperate oceans   Maybe it is due to the ice at Alaska melting so fish are moving up there due to nutrients avaliability - Why most strongly is wintertime= = Oct-Feb is wintertime in Alaska - Northern movement of sea ice   **Changes in oxygen** - Warmer water holds less oxygen than cold water - Water breathing animals are oxygen constrained - Water has lower O2 concentration than air - Water has much higher vicosity than air - Everything water breathing animals do is limited by ability to obtain O2 - Growth, reproduction, feeding, activity patterns, behavouir - More big fish spp in temperate areas than tropics - Gill oxygen limitation theory Therefore : the warmer the water, the less the O2 = smaller the fish     **Acidification** Oceans to become 150% more acidic by the end of the century - Harmful to oysters, corals, plankton and shellfish that grow hard shells made of calcium carbonate. Higher acidity (lower pH) dissolves those shells or reduces shell formation - Zooplanktion are a fundamental link in food webs - Lower pH affects the development of otoliths (ear bones) critical ??? (SEE SLIDE) US Alaska red king crab = big money/ huge fishery - Survival rate of crab embryonies which subsequently recuit to the first stage US pacific coast clams and scallops - Malformed and eroded shells     **Sea level rise** - Thermal expansion of ocean water mass - Melting of polar ices sheets - Globally risen 20cm since 1880 - The rate of sea level rise has doubled from 1.4mm/yr to 3.5mm per year - By 2011: - Conservatively (guaranteed) = 1-2 meters - Potentially (likely, west Antarctic ice shelf melt): 3-15 m - Then add in storm surges (See impacts if cyclones in Florida) So what about fisheries? - More inundated coastal areas - More habitats?? - More shallow water fishing areas? - Impacts on coral reefs and coastal mangroves - Current shells waters will be deeper - Reefs will be deeper - Speed of sea level rise vs vertical growth rates - Potential consequences - Reduced coastal storms surge protection - Reduced coral reefs and mangroves fish habitat   **Water currents** Gulf streams has slowed down by 20% over the last few decades - Larval export - Transoceanic migrations - Weather and climate in Europe - Gulf streams are keeping Europe warms, so if it stops Europe could potentially get a iceage - The gulf stream is one of the main drivers of global conveyer belt of ocean circulation.. - Guaranteed to have massive impacts we cannot being to predict   **Changes in weather patterns** - Stronger and more frequent storm and extreme events