GEOG 300 1st Edition Lecture 3Global Fishing CrisisFAO’s - Capture fisheries and aquaculture supplied the world with 158 million tons of fish in 2012o 136 million tons was food for people.- World fish food supply has grown dramatically in the last five decadeso Average growth rate of 3.2 percent per year in the period 1961–2012o Outpacing the increase of 1.6 percent per year in the world’s population. - World per capita food fish supply increased from an average of 9.9 kg (live weight equivalent) in the 1960s to 19.2 kg in 2012.- China has been responsible for most of the increase in world per capita fish consumptiono Owing to the substantial increase in its fish production, particularly aquaculture, despite a downward revision of China’s production statistics for recent years- Ecologyo A multidisciplinary, integrative and holistic science that has a deep in biology.o The study of environmental system Sometimes called the economy of natureo Why learn it? All of us live to some degree in a natural or at least partly natural ecosystem Can be very useful to help us understand what these changes are, what the implications might be for various ecosystems.- Trophic levelo Range from a definitional value of one for primary up to a level of five for marinemammals and humans.o Defined as the position of an organism in the food chain, determined by the number of energy-transfer steps to that level. o Role of fishes within ecosystems is largely a function of their size: small fish are more likely to have a vast array of predators than very large ones.- Bycatch- incidental catching, discarding, or damaging of living marine resources when fishing for targeted species.o It is estimated that 6 billion pounds of unwanted fish were discarded each year during the 1980s and early to mid-1990s- Jacksono The crises of the marine systems have long rooted causes.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.o These causes go back to a time in which we did not use the tools of modern ecological investigations, we need to reconstruct the past. o The author uses the tools of paleoecological, archeological, and historical reconstructionso Humans are not the only agents of change in natural systems: o “Not all ecological change is anthropogenic. Natural conditions in the oceans fluctuate greatly and sometimes suddenly on time scales that extend for decades to millennia.” o This complicates the analysis – in trying to understand the effect we have on the environment we need to separate the two:o “Changes caused by humans are the signal and natural variability constitutes the noise that obscures the human footprint.”o Jackson focuses on benthic communities:o Dwelling on, or relating to, the bottom of a body of water; living on the bottom ofthe ocean and feeding on benthic organismso As opposed to pelagic communitieso Living and feeding in the open seao Associated with the surface or middle depths of a body of watero Free swimming in the seas, oceans or open waterso Not in association with the bottomo Many pelagic fish feed on planktono Jackson focuses on “benthic communities because extreme overfishing of pelagic species such as Atlantic whales, tuna, salmon, and herring is well known.- Caribbean coral reefso Coral reefs are the largest durable biological constructions on earth. o Coral reefs are the most diverse marine ecosystems in terms of the number of species they support.o Reef fisheries provide food for millions of peopleo Reef structures protect shorelines from tropical storm swells, o They are a very important source of tourism (divers and snorkelers) bringing dollars for local Caribbean economies. o Pharmaceutical companies are interested in coral reefs as potential sources of newdrugs.o In the reef, species composition was stable for at least 125 thousand years, until the collapse in the 1980so The collapse: long lived corals tend to disappear, what corals remain are short-lived.o The collapse occurred in phaseso Overfishing allowed the sea urchin Diadema to increase in abundance; o The sea urchin became the main eater of the macroalgae, and it compensated for loss of herbivorous fishes;o An unidentified pathogen caused mass mortality of Diadema, and the macroalgae took over, because there was nothing eating them.- Caribbean Seagrass Meadowso Less diverse than coral reefs, but much bigger in area.o Seagrasses enhance sediment stability decrease wave energy increase water clarity provide forage, habitat, and nurseries for diverse and abundant invertebrates and fisheso Seagrasses along the Florida coast experienced mass mortality in the 1980s because of a wasting disease.o Mortality was  positively density dependent  correlated with high temperatures and salinities,  sulfide toxicity,  self-shading,  hypoxia (low oxygen),  Infection by the slime mold Labyrinthula sp.o All the possible factors except salinity and temperature have changed greatly because of the massive exploitation of sea turtles and manatees.o Concentration of sulfides in sediments increases with accumulation of organic material that may also cause anoxia (no oxygen) within sediments and hypoxia (low oxygen) of overlying waters, but green turtles greatly decrease accumulation of organic matter in sediments- Sea Turtle Fisherieso The green turtle was the turtle of choice. o The meat was flavorful, and the fatty tissue found under the shell was dried and used to make the turtle soup popular with European royalty in the 18th and 19th centuries. o The name "green turtle" refers to the color of this fat, not the shell. o Because the green turtle could be carried alive for extended periods, some believe it may have provided the meat needed to enable early sailors to explore, colonize, and exploit the New World on their extended voyages- Chesapeake Bayo Largest and historically most productive estuary in North America. o It used to be home to very extensive meadows of seagrasses, oyster beds, clams, blue crabs, and fish o In the past century, these declined precipitously, while abundance and production of phytoplankton, eutrophication, and episodes of hypoxia and anoxia correspondingly increased.o The Bay problems are due to both overfishing and increasing runoff of freshwater,nutrients, and sediment from the land, but physical conditions are extremely variable and