BIOL 316 MIDTERM SET EXAM 2025

BIOL 316 MIDTERM SET EXAM 2025 Reproduction Effort - -investment of energy into reproduction. Can be measured in several ways: number of eggs per female, biomass of eggs per female, and GSI. Often discussed in terms of whole energy budget Gonad somatic Index (GSI) - -weight of the gonads expressed as a percentage of body mass. One of the most useful measures of reproductive effort Whole Energy Budget Equation - -C = Pr + Pg + R + U + F. Breakdown of what energy is expended on. C = input of energy (caloric), Pr = energy into reproduction, Pg = energy into growth, R = energy into metabolism, U = energy into urinary and non-fecal excretions, F = energy into fecal excretions Why is it important to understand the energy budget - -Growth slows as fish reach maturity (then begin expending more E for reproduction). Can indicate the age of maturity Energy budget can also show how stress affects reproduction. Stress causes an elevation in metabolism (R) - less E available for reproduction (Pr) Semelparity and Iteroparity - -Semelparity: one time investment into reproduction. i.e. Pacific salmon. Good strategy for stable conditions, or when there are compensatory mechanisms to make up for failure caused by fluctuating environmental conditions. Compensatory mechanisms = overlapping generations and straying Iteroparity: several investments into reproduction. Atlantic salmon. Good strategy when environmental conditions are not stable. If unsuccessful in one attempt, can try again. Oviparous and Viviparious - -Oviparous: lay eggs. Many offspring - Fish with large numbers of eggs/offspring may recover better from overfishing Viviparous: females release hatched young (well-nourished juveniles/young adults). Fewer offspring BOFFFF - -Big old fat fecund female fish Bony Fish - Egg Protection and Parental Care - -Typically some form of parental care. Guarding of eggs and offspring is most common form. Other parental care behaviours include nest building, cleaning of spawning substrate, fanning eggs, internal gestation, oral brooding, and burying eggs BIOL 316 BIOL 316 Explain why most of the mortality in fish species occurs in early-life history stages (5) - 1) Rapid growth to survive - small = most susceptible to predation 2) Rapid growth is dependent on the switch from phytoplankton to larger prey (ex. Zooplankton and prey fish). Growth is dependent upon location (prey density) - at the mercy of their environment. 3) More susceptible to changes in pH and salinity in early life history. Can be harmed by acid-run off, acute changes in temperature, and currents/wave actions (environmental disturbances). 4) A lot of mortality occurs at this time due to starvation. Feeding is limited by: development of the sensory systems and feeding apparatus (gape size), and the ability to move/swim well enough to capture food. 5) Competition: all spawn in the same area, at the same time. Those who spawn earlier have an advantage - have more time to grow and can prey on those who spawn later. Competition is high. Recruitment - -Refers to the relative number of fish that survive the early life history challenges to become a part of the adult population. Determines how many fish are added to the overall population in a given year Year Class Strength - -Relative success of recruitment in any given year. Number of new recruits per spawning year. Recruitment Models - -used to describe/determine recruitment. Used to understand biotic and abiotic factors that affect recruitment. Used to determine the number of fish that can be harvested sustainably, and if fisheries can improve recruitment (i.e. add large rocks to rivers to increase spawning) Models to Describe Relationship between Number of Spawners and Number of Predicted Recruits (3) - -Exponential: slope = maximum reproductive rate. Each pair of spawners produces many recruits to the population. Only a few adults can produce a large number of eggs/recruits Beaverton-Holt: exponential growth when population is small - slope near origin represents maximum reproductive rate. Also incorporates maximum carrying capacity that will be approached - no more recruits can be added regardless of number of spawners and number of eggs deposited. Assumes some type of juvenile density dependence is a limiting factor, i.e. a limited number of nursery areas available. Impact of harvesting adult fish decreases as we move closer to the righthand side of the curve Ricker: similar to Beaverton-Holt, but when recruits reach a maximal level, recruit numbers decline with greater number of spawners. Due to limited resources and competition - few fish will survive their first winter because they are unable to gain BIOL 316 BIOL 316 enough resources and grow large enough when food supply is limited due to density/competition. Also chance of cannibalism Specific Dynamic Action (SDA) - -energy cost of breaking down (hydrolyzing) large complex protein molecules to AAs and synthesizing new proteins (growth) following a meal. SDA increases with amount of protein in the diet. Can be measured as an increase in O consumption (MR) following a meal Piscivorous Fish - -carnvivorous fish that consumes primarily fish prey Primary Piscivores - -Shift to piscivory within the first few months of life Secondary Piscivores - -Shift to piscivory later in life. Keast proposed its simply a way of maintaining E efficiency in feeding. For large fish, fish are eventually the only large enough prey (optimal foraging theory) Trophic Cascade Model - -model feeding behaviour, predation, foraging, habitat preferences. Used to predict what would happen if there's a change in community structure (i.e. invasive species, species is overharvested or goes extinct). Quite theoretical Components of Predation - -Prey have to be located, pursued, captured, handled/manipulated, and digested. Selective Predation/Specialists - -consumption of prey in different proportions than available in surrounding habitat Random Feeding/Opportunistic Feeders - -predators feed indiscriminately on prey in accordance with relative availability Optimum Size Range - -· predator will attempt to eat most of their prey in this range Optimal Foraging Theory - 2 Basic Predictions - -1) Predators should prefer prey that yield more E per unit handling time 2) As abundance of higher value prey increases, lower value prey should be dropped from the diet and predators should become more selective Ideal Free Distribution Theory (IFD) - -has guided studies of habitat selection in fish. Based on idea that fish should select habitats that maximize their fitness - equated with feeding rates in simplest IFD models, and the assumption that feeding rates are density dependent. Expect the number of predators in an area to be proportional to the total food input (food available) in that area. Risk of predation is also important. Low predation - can forage in open waters to maximize E gain. High predation - forage in protected areas with lower E gain BIOL 316 BIOL 316 The µ/g Rule - -habitat choice that maximizes a fish's fitness is the habitat that minimizes the ratio of mortality rate (µ) to growth rate (g). Takes predation into account in predicting habitat selection Hagfish - -not really fish, not even true vertebrates. ~60 species. Descended from ancient lineage ~500mya. Jawless, no paired fins, gills open through pores. Scavengers. Eel-like shape. Lampreys - -true vertebrates. More closely related to jawed fish (cartilaginous and bony) than hagfish. ~41 species. Some are parasitic. Complicated life cycle. Bad reputation with humans - parasitic. Jawed Fish - 2 Main Groups - -Cartilaginous Fish (elasmobranches and chimeras) and Body Fish (lobe finned and ray finned - teleosts are in ray finned) What group of fish contains most of the species that are important to recreational and commercial fisheries? - -Teleosts (Bony fish, ray-finned) that are piscivorous (carnivorous, primarily eat other fish species) Single Species Approach - -most fisheries up until recently operated this way. Only monitored one species. Instead, should take into account ecological interactions (ecosystem management) Ecological Interactions Approach - Ecosystem Management - -general description for a more sustainable approach to the management of natural resources. Difficulty with approach: often have limited information about the complete ecology of ecosystems. Also often have trouble determining what tools/techniques should be used for new approaches. Trophodynamics - -study of fluxes of nutrients and E in ecosystems. Food webs and food chains are 2 approaches used in trophodynamic studies. Both describe trophic relationships among organisms in communities/ecosystems - major focus of trophodynamic studies. Provide information about interactions among organisms in ecosystems Food Chains - -one of the earliest attempts to understand how ecosystems function. Combine species into groups within trophic levels. Arranged in a linear chain. Often used to describe fluxes (arrows) and transfer efficiencies (given as a fraction or %) between trophic levels. Allow quantitative comparisons between different systems (i.e. open ocean vs coastal) in terms of trophic level and efficiency of food chain transfer Arrows represent direction of energy flux, Percentages represent transfer efficiencies of energy fluxes BIOL 316 BIOL 316 Weaknesses of Food Chain Approach (4) - -1) Many species feed at more than 1 trophic level - feeding relationships are more appropriately represented as food webs 2) Implies that size or productivity of consumer populations are driven by primary productivity (bottom up). Other processes however, such as predation, may also influence population size or productivity at different trophic levels (top-down effects) 3) Designating an efficiency value for E transfer between trophic levels is unrealistic because different organisms/species and developmental stages differ in terms of ecological efficiencies 4) Materials not used by the organisms in food chains are not necessarily lost from the ecosystem (as implied by food chain depiction). Much of the dissolved and particulate organic matter released by consumers returns to the food web via a microbial loop. i.e. microzooplankton help to recycle organic matter and make it available again to organisms at higher trophic levels Food Webs - -: illustrate the feeding relationships within entire communities of organisms - can see interactions between species. Detailed food web analyses have become the most common way of depicting feeding relationships in ecosystems. Often used for ecosystem management. Invasive species throw off food webs massively. Each time one is introduced, the food web needs to be re-constructed Challenges/Limitations of Food Webs (5) - -1) Diets vary in time and space, but food webs imply steady state conditions 2) Many small dietary items (dissolved organic matter, detritus, fish eggs, bacteria, etc.) are poorly qualified or under-represented. Important pathways therefore may be underestimated 3) Trophic fluxes between organisms are represented, but other factors besides feeding (migration, fishing harvest, recruitment) may also have an important impact on relative population sizes and web structure - not incorporated 4) The boundaries of food webs are often hard to define (especially due to migration) 5) Factors such as climate (season) can have large impacts on primary productivity at the base of the food web, and therefore affect fluxes through the system Gut Content Analyses (Visual and Molecular) - -Visual: analysis of stomach (gut) contents to determine relationships in food webs. Primarily visual. Done by fisheries technicians. BIOL 316 BIOL 316 Molecular: provides more improved information compared to simple visual observations (2x), but most of the limitations still apply, even if larger food items are fully identified. Limitations of Gut Content Analysis - -1) Provides only 'snapchats' in space and time 2) Duration of snapshot is variable depending on time required for gut turnover in a species 3) Some dietary items such as detritus and gelatinous plankton aren't included in these analyses, but can be important 4) Organisms at the base of food webs are difficult to characterize and are often lumped together inappropriately. Important source of error in properties of food webs Stable Isotope Analyses - -approach to understand food web structure. C and N exist in two stable isotopic forms that differ in atomic mass. Each has one isotope that has a heavier atomic mass. These differences in mass influence the strength of chemical bonds (bonds involving the heavier isotopes are slightly stronger because they have less vibrational energy) and therefore the way the different isotopes are affected by processes such as respiration, catabolism, excretion, etc. As a result of this, the tissues of organisms become slightly enriched in the heavier isotopes after feeding on an organism at a lower trophic level. This means the ratios of isotopes in tissues can tell us something about the relative position of organisms in the food web. Stable Isotope Fingerprints - -when stable isotope analyses are conducted on organisms in a particular ecosystem, the resulting data produces a 'fingerprint' of the food web because the plant components differ in their relative abundance of the isotopes. This provides an indication of trophic level. The stable isotope fingerprints of similar ecosystems tend to be very similar. Similarities indicate fingerprints provide repeatable and meaningful information about food webs. Advantages of Stable Isotope Analyses (6) - -1) Compared to traditional dietary analyses like gut content analyses, the tissues sampled turnover relatively slowly. This means that information about diet from stable isotopes covers substantial periods of time (a year or more in juvenile/adult fish, slightly less in very young fish) 2) Data can be useful for assessing the importance of major pathways in food webs 3) Good for determining whether 2 species feed similarly or dissimilarly 4) Indicates the components of the diet that are actually assimilated (not just ingested) 5) Good for determining the trophic level at which an organism is feeding 6) Good for determining spatial variation in nutrition - how separate areas/ecosystems differ in terms of the nutrition they provide Analysis of Fatty Acid Profiles - -useful indirect method to gain information about organism diets. Provides information on a time scale (weeks to months) that is BIOL 316 BIOL 316 intermediate to gut content analysis (hours to days) and stable isotope analysis (months to years) Basic Principles of Fatty Acid Profile Analysis (3) - -1) Consumed lipid is usually stored as FFAs that are largely unchanged from those within the consumed organism 2) There are many different types of FAs in organisms 3) The organism's FA profile is largely determined by diet Stock - -self-sustaining population of a species that occurs within a defined region. Stocks of fish are spatially separated to a degree where breeding between stocks cannot occur, even if they belong to the same species Migration - -movement of indivdiuals and populations from one area/habitat to another. Movement has a cyclical element (annual or life cycle stage) that distinguishes it from dispersal Oceanodromous - -migration occurs entirely within sea Potadromous - -migration occurs entirely within FW Diadromous - -migration between sea and FW. Falls into different subcategories... Anadromy: most feeding and growth takes place in the sea, prior to the migration of adults to FW to reproduce. Typically no feeding by adults in FW, at least towards somatic growth. Principle feeding and growing biome (sea) different from the reproductive biome (FW). i.e. salmon Catadromy: primarily feed and grow in FW prior to the migration of adults to the sea to reproduce. Principle feeding and growing biomes (FW) differ from reproductive biome (sea). i.e. American eel Why Do Fish Migrate (1) - -may have evolved in order to take advantage of some environments being better suited for activities at different life history stages (feeding, growing, spawning, etc.) - population size is not limited to resources in a single habitat. Improved survival and reproductive success is the ultimate selective advantage of migratory behaviour. Anadromous Salmon Life Cycle - -Migratory. Complex life histories. Spawn in the headwaters of FW streams. After hatching, alevins remain in the gravel for a few weeks before beginning to live and feed in the streams. In some species, alevins move quickly downstream to the sea, in others they may spend several years feeding and growing in FW before they become smolts and move to sea. Life at sea is spent feeding and growing - can last between 1-6 years depending on the salmon. Salmon re-enter the rivers they were born in once mature and move upriver for weeks to months - during this BIOL 316 BIOL 316 time they don't feed and E is allocated towards maturing reproductive organs. In most species of Pacific salmon, spawning is followed by death. In other species like Atlantic salmon, many individuals survive spawning. How do Migrating Salmon Find their Way (3) - -salmon have precise homing abilities and are able to return to the exact area of the stream in which they were born. 1) In open ocean, salmon use a magnetic sensory system located in the nasal area to orient themselves according to the Earth's magnetic field 2) Salmon can also use compass mechanisms associated with the sun and stars to help them find their way in the ocean 3) The final leg of the salmon's journey involves olfaction. Using their olfactory epithelium, salmon detect the appropriate chemical properties of their home stream. Salmon are adapted to store an olfactory memory of their home stream during early life history stages (around the parr-smolt transformation) via a process known as olfactory imprinting Olfactory Imprinting - -involves surges of thyroid hormone during early life history stages that allow young salmon to take a chemical 'snapshot' of their environment. As adults, they use this olfactory imprint to determine the exact location of their birthplace Why are Salmon so Precise in their Migration? (1) - -It's a selective advantage - they already know the stream is good habitat for rearing young. Standard Floy Tags - -external tags that possess a unique code that identified the individual fish. In order for the tag to produce information, the fish needed to be caught again somewhere at a later time. Provided valuable information about movements, but had a lot of limitations Acoustic Telemetry - -transmitters and receivers involved are more sophisticated. If a fish comes within 0.5 km it's picked up. Network of receivers in an area piece together movements of fish. Lots of information Data Storage (Archival) Tags - -more recent versions of tags. Can monitor information about light levels, pressure, T, etc., and store that information within the tag. When the tag/fish is recovered, the information can be downloaded Pop-Up Tag - -another type of data storage tag. Called pop-up tags because they can be programmed to separate themselves from the fish and pop up to the surface after a fixed period of time. Information in tag is then transmitted to a satellite and can be obtained by the researcher. Very expensive. Aquaculture - -domestication of wild stocks for human consumption. Ownership of stock. Deliberate control in husbandry. BIOL 316 BIOL 316 One of the most important fisheries issues on the planet. Seems like the perfect solution to the harvest limit of wild fish on the surface, but there are many issues with it. Controversial issue. Biological Issues associated with Aquaculture (6) - -1) Source of Feed: in many aquaculture operations, large carnivores are fed fishmeal that largely consists of wild prey species. This practice puts further pressure on wild stocks and natural food webs. Recall 'fishing down marine food webs' is one of the major problems faced in fisheries a. The amount of fish meal and fish oil used to create feed for carnivores such as salmon are ~45% and 25% respectively. This could be much less (10%) because some species (carp, tilapia) are omnivores. For years, to produce a pound of salmon we had to feed it 3lbs of wild fish. These numbers have improved in recent years with new feeds but creating feeds for carnivorous fish with fish-in:fish-out ratios of 1 is a challenge. Also a challenge to get enough fish meal/oil to support aquaculture without overfishing. 2) Escapees: damage to cages by storms or predators can result in large numbers of farmed fish escaping into the wild. Large numbers can now be found among wild stocks. Creates issue: introduction of exotic species, genetic dilution of wild stocks, transfer of disease, etc. 3) Habitat Modification: in some countries, vast areas of mangroves and coastal wetlands have been converted to fish and shrimp farms. These originally provided nursery to many wild fish species, flood control, and water purification 4) Impacts of Wastes: uneaten food and feces from aquaculture operations have big impacts on local water chemistry (nutrient pollution, N wastes). This is most important in small waterbodies, or in areas where aquaculture operations are extremely concentrated 5) Use of Transgenic Fish: there is pressure to use transgenic fish that grow faster (GH), survive in colder climates (antifreeze proteins), and/or are resistant to certain diseases à economic reasons. However, transgenic escapees are an issue, as well as public con Potential Solutions for Aquaculture (3) - -Feed: put greater emphasis on herbivorous and omnivorous species that are less reliant on fish products in feed (carp, tilapia). Also more research into developing substitutions for fish-based food. Developing greener feeds that don't rely on wild prey species to the same extent, or all - eliminate wild fish component from aquaculture diets. Biggest challenge will be to produce fish that are competitively priced with those from current practices (start-up and operating costs of new facilities are relatively high) Escapees: strict biosafety measures for exotics. Sterilization techniques. Improved cage security BIOL 316 BIOL 316 Habitat: stricter site regulations. Challenge in developing countries - important for development of wetlands and mangrove areas. Limit density of operations in sensitive coastal areas Growth - -change in size (length or weight) over time. Fisheries biologists typically look at length, as weight can change with a meal Growth - Energetic Definition - -change in calories stored as somatic and reproductive tissue. Helps us understand factors that effect growth Simplified Energy Equation - -I = M + G + E I = ingested food energy (calories), M = energy expended for metabolism (body maintenance and repair, SDA (digesting food), and movement), G = energy expended for growth, E = energy excreted Factors Influencing Growth (11) - -1) Water Temperature (T): one of the most important environmental variables for growth. In many species, growth increases with T up to a point, then falls off when T approaches the maximum preferred range for that species. Growth is typically maximal near pre