David Henry Cushing | |
---|---|
Born | Alnwick, England | 14 March 1920
Died | 14 March 2008 88) England | (aged
Nationality | English |
Alma mater | Balliol College, Oxford University |
Known for | Match/Mismatch Hypothesis North Sea Herring Fisheries |
Awards | Fellow of the Royal Society (1977) Rosenstiel Medal (1980) Medal of Albert 1er of Monaco (1984) American Fisheries Science Excellence Award (1987) ECI Prize Winner (1992) German Ecology Prize (1993) |
Scientific career | |
Fields | Fisheries Biology |
Institutions | Journal of Plankton Research (Founding Editor) CEFAS ICES |
David Henry Cushing FRS [1] (1920-2008) was an English born fisheries biologist, who is credited with the development the match/mismatch hypothesis as an explanation for reduced fish stocks as associated with climatic variability. David Cushing was the first to demonstrate what we now know as "recruitment overfishing" through his work on the collapse of the North Sea herring.
Cushing was born in Alnwick, England. His father was an English teacher and his mother was a nurse. By way of his own desire to be a naturalist, his father's desire for him to become a diplomat, and his mother's desire for him to become a doctor, Cushing found a great interest in fisheries biology and management. Cushing also served in the British military in the Royal Artillery (1940–1945) and the Royal Fusiliers (1945–1946). Cushing is survived by his wife, Diana Antona-Traversi, whom he married in 1943, and his daughter. [2] [3]
Cushing received his lower education from Duke's School (Alnwick) and the Royal Grammar School (Newcastle upon Tyne) and received his PhD in 1950 from Balliol College at Oxford University. His PhD dissertation focused on the vertical migration of zooplankton. [4]
After receiving his PhD, Cushing worked primarily for government organisations that oversaw the fisheries in Great Britain. For most of his career (1946–1980), he worked for the Centre for Environment, Fisheries, and Aquaculture Science (CEFAS). At CEFAS, he held the positions of scientific officer, deputy director, and as the head of fish population dynamics. His last position allowed him to focus primarily on factors influencing the stock dynamics of local fisheries and the management strategies those fisheries open. [4]
Cushing, although not directly employed by, worked closely with the International Council for the Exploration of the Sea (ICES). At ICES, Cushing held positions on advisory committees for fisheries management and marine pollution. He also chaired the biological committee and was the head of the herring workgroup. [4]
The most prestigious position that Cushing held was that of the founding editor of the Journal of Plankton Research, which he held from 1979 to 2001. [4]
Acoustics were greatly improved upon during World War II so as to be used as a tool to detect unfriendly vessels and underwater hazards. After the war, acoustic detection was seen as a tool that could assist fisheries biologists to sample stock sizes. Cushing investigated the mechanisms that permitted the acoustic returns from the signalling devices to the fish and back. Through experimental procedures, using materials such as meat-filled condoms and air-filled balloons, Cushing determined that greater than 50% of the acoustic return was from the swimbladder of the fish. Cushing and colleagues also determined that it was possible to resolve, on the species level, the identity of a mass of fish through precise acoustic signals. [5]
The match/mismatch hypothesis was coined by Cushing as a result of noticeable variations in fish stock recruitment. The hypothesis focused on the timing, as a function of climate, of the blooms of primary producers (i.e. phytoplankton). Blooms of phytoplankton directly influence the increased population sizes of zooplankton, as the phytoplankton are the primary food source for zooplankton. Most pelagic fish, in their larval stages, feed directly upon the phytoplankton and zooplankton. So as logic follows, large populations of phytoplankton will support large populations of zooplankton, and the presence of both will sustain larval fishes. As Cushing noticed, however, there are climatic influences where temperature anomalies will inhibit phytoplankton blooms, or impact the range of the bloom. When such events occur, they will have cascading effects that will influence the ability for larval fish to develop, thus reducing the number of fish that recruit into an existing population. [6] With the previously mentioned events, the "match" portion of the hypothesis occurs when plankton blooms occur just prior the hatching of the fish larvae. In a "match" situation, the fish larvae are able to feed on large quantities of plankton, thus increasing their potential for successful recruitment. The "mismatch" portion of the hypothesis occurs when plankton blooms occur either earlier than usual, later than usual, or simply in far lesser quantities than expected. As a result, there are less prey for the fish larvae to feed upon, and the success of a recruitment event is severely diminished. [7]
The match/mismatch hypothesis is featured in many of Cushing's writings, however the most influential purpose of the hypothesis is that of awareness of climate change and fisheries management. The intent of the hypothesis was to explain climate induced temperature anomalies (as a result of climate change) on fish stocks and the proper management strategies that could be associated with such changes. With some level of predictability, then, fish stocks would then avoid over-exploitation and be harvested at sustainable levels. [8] [9]
Plankton are the diverse collection of organisms found in water that are unable to propel themselves against a current. The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucial source of food to many small and large aquatic organisms, such as bivalves, fish, and baleen whales.
Menhaden, also known as mossbunker and bunker and "the most important fish in the sea", are forage fish of the genera Brevoortia and Ethmidium, two genera of marine fish in the order Clupeiformes. Menhaden is a blend of poghaden and an Algonquian word akin to Narragansett munnawhatteaûg, derived from munnohquohteau, referring to their use of the fish as fertilizer. It is generally thought that Pilgrims were advised by Tisquantum to plant menhaden with their crops.
Phytoplankton are the autotrophic (self-feeding) components of the plankton community and a key part of ocean and freshwater ecosystems. The name comes from the Greek words φυτόν, meaning 'plant', and πλαγκτός, meaning 'wanderer' or 'drifter'.
Zooplankton are the animal component of the planktonic community. Plankton are aquatic organisms that are unable to swim effectively against currents. Consequently, they drift or are carried along by currents in the ocean, or by currents in seas, lakes or rivers.
The spring bloom is a strong increase in phytoplankton abundance that typically occurs in the early spring and lasts until late spring or early summer. This seasonal event is characteristic of temperate North Atlantic, sub-polar, and coastal waters. Phytoplankton blooms occur when growth exceeds losses, however there is no universally accepted definition of the magnitude of change or the threshold of abundance that constitutes a bloom. The magnitude, spatial extent and duration of a bloom depends on a variety of abiotic and biotic factors. Abiotic factors include light availability, nutrients, temperature, and physical processes that influence light availability, and biotic factors include grazing, viral lysis, and phytoplankton physiology. The factors that lead to bloom initiation are still actively debated.
Sir Alister Clavering Hardy was an English marine biologist, an expert on marine ecosystems spanning organisms from zooplankton to whales. He had the artistic skill to illustrate his books with his own drawings, maps, diagrams, and paintings.
A salp or salpa is a barrel-shaped, planktonic tunicate in the family Salpidae. It moves by contracting, thereby pumping water through its gelatinous body, one of the most efficient examples of jet propulsion in the animal kingdom. The salp strains the pumped water through its internal feeding filters, feeding on phytoplankton.
The Atlantic menhaden is a North American species of fish in the herring family, Clupeidae.
Pelagic fish live in the pelagic zone of ocean or lake waters—being neither close to the bottom nor near the shore—in contrast with demersal fish that live on or near the bottom, and reef fish that are associated with coral reefs.
In biological oceanography, critical depth is defined as a hypothetical surface mixing depth where phytoplankton growth is precisely matched by losses of phytoplankton biomass within the depth interval. This concept is useful for understanding the initiation of phytoplankton blooms.
The Centre for Environment, Fisheries and Aquaculture Science (Cefas) is an executive agency of the United Kingdom government Department for Environment, Food and Rural Affairs (Defra). It carries out a wide range of research, advisory, consultancy, monitoring and training activities for a large number of customers around the world.
Calanus finmarchicus is a species of copepod and a component of the zooplankton, which is found in enormous amounts in the northern Atlantic Ocean.
The Australian Continuous Plankton Recorder (AusCPR) survey is a joint project of the CSIRO and the Australian Antarctic Division, DEWHA, to monitor plankton communities as a guide to the health of Australia's oceans.
Forage fish, also called prey fish or bait fish, are small pelagic fish which are preyed on by larger predators for food. Predators include other larger fish, seabirds and marine mammals. Typical ocean forage fish feed near the base of the food chain on plankton, often by filter feeding. They include particularly fishes of the order Clupeiformes, but also other small fish, including halfbeaks, silversides, smelt such as capelin and goldband fusiliers.
The stable ocean hypothesis (SOH) is one of several hypotheses within larval fish ecology that attempt to explain recruitment variability. The SOH is the notion that favorable and somewhat stable physical and biological ocean conditions, such as the flow of currents and food availability, are important to the survival of young fish larvae and their future recruitment. In the presence of stable ocean conditions, concentrations of prey form in stratified ocean layers; more specifically, stable ocean conditions refer to “calm periods in upwelling ecosystems ” that cause the water column to become vertically stratified. The concept is that these strata concentrate both fish larvae and plankton, which results an increase of the fish larvae feeding because of the density-dependent increase in predator-prey interactions. Lasker is attributed with constructing this hypothesis in the late 1970s by building on previous larval fish research and conducting his own experiments. He based the SOH on case studies of clupeid population fluctuations and larval experimentation.
Ichthyoplankton are the eggs and larvae of fish. They are mostly found in the sunlit zone of the water column, less than 200 metres deep, which is sometimes called the epipelagic or photic zone. Ichthyoplankton are planktonic, meaning they cannot swim effectively under their own power, but must drift with the ocean currents. Fish eggs cannot swim at all, and are unambiguously planktonic. Early stage larvae swim poorly, but later stage larvae swim better and cease to be planktonic as they grow into juveniles. Fish larvae are part of the zooplankton that eat smaller plankton, while fish eggs carry their own food supply. Both eggs and larvae are themselves eaten by larger animals.
Raymond (Ray) John Heaphy Beverton CBE FRS was an important founder of fisheries science. He is best known for the book On the Dynamics of Exploited Fish Populations (1957) which he wrote with Sidney Holt. The book is a cornerstone of modern fisheries science and remains much used today. Beverton's life and achievements are described in detail in several obituaries written by prominent figures in fisheries science.
Clupea is genus of planktivorous bony fish belonging to the family Clupeidae, commonly known as herrings. They are found in the shallow, temperate waters of the North Pacific and the North Atlantic oceans, including the Baltic Sea. Two main species of Clupea are currently recognized: the Atlantic herring and the Pacific herring, which have each been divided into subspecies. Herrings are forage fish moving in vast schools, coming in spring to the shores of Europe and America, where they form important commercial fisheries.
A planktivore is an aquatic organism that feeds on planktonic food, including zooplankton and phytoplankton. Planktivorous organisms encompass a range of some of the planet's smallest to largest multicellular animals in both the present day and in the past billion years; basking sharks and copepods are just two examples of giant and microscopic organisms that feed upon plankton. Planktivory can be an important mechanism of top-down control that contributes to trophic cascades in aquatic and marine systems. There is a tremendous diversity of feeding strategies and behaviors that planktivores utilize to capture prey. Some planktivores utilize tides and currents to migrate between estuaries and coastal waters; other aquatic planktivores reside in lakes or reservoirs where diverse assemblages of plankton are present, or migrate vertically in the water column searching for prey. Planktivore populations can impact the abundance and community composition of planktonic species through their predation pressure, and planktivore migrations facilitate nutrient transport between benthic and pelagic habitats.
The lipid pump sequesters carbon from the ocean's surface to deeper waters via lipids associated with overwintering vertically migratory zooplankton. Lipids are a class of hydrocarbon rich, nitrogen and phosphorus deficient compounds essential for cellular structures. This lipid carbon enters the deep ocean as carbon dioxide produced by respiration of lipid reserves and as organic matter from the mortality of zooplankton.