Resource Management Final

Population Dynamics

study of how and why populations change in size and structure over time.

Why is it important to understand population dynamics?

Essential for managing natural resources, planning for human infrastructure, and protecting biodiversity

Trophic Pyramid

graphical representation that shows organism position in the food web and the flow of energy between organisms. (Producers —> primary consumers/herbivores —> secondary consumers/carnivores —> tertiary consumers/bigger carnivores —> apex predators)

Trophic cascades and their consequences

Trophic cascade is when adding or removing top predators causes indirect, ripple-effect changes across multiple lower levels of a food web. Consequences include habitat degradation, loss of biodiversity, reduced carbon storage, and altered nutrient cycling.

Where are the sea lions?

Severe decrease in population since the 1970s (especially in Western population), Eastern pop. had increase

What was the problem for the sea lions?

Sea lions mainly eat herring, a fatty fish, for sustenance. In 1970, US government banned commercial fishing of Pollock from SW coast of Alaska to Aleutian Islands, and pollock populations increased while herring decreased. Pollock is lean and cannot fully sustain sea lions.

How was the problem noticed and identified for the sea lions?

What tools were used to control/identify causes for the sea lions?

What were consequences caused by sea lion decline?

What happened to the sea otters?

What was the problem for the sea otters?

How was the problem noticed and identified for the sea otters?

What tools were used to control/identify causes for the sea otters?

What were consequences caused for sea otters?

Conch historical uses

High value source of protein, harvested since pre-Columbian time, internationally traded with Hispaniola in 1800s

Spiny lobster historical uses

Bait (caught w/ bully nets), 1960s began free diving and hook use, lobster became very commercially valuable

Queen conch biology

Pelagic life stages (highly susceptible to drift), eggs laid in mass, metamorphosis triggered by compounds in red algae

Queen conch biology role in management

Hard to find in faunal stages (buried in sand), habitat requirements vary by age, have reproductive migrations and aggregations, can be inaccurately aged, if conch are knocked then cannot easily tell if they were in size limits

Conch trends

Large export for TCI (supply 10% of global supply), over $3.5 million/yr, status in TCI is decreasing

TCI conch fisheries

~250 full and part time fishers, 200 small boats, no large fleets. Collect by hand, knock in boat, discard shells. Take to processing plant and sell.

TCI industry history and trends

Salt dominated until 1915-1919 when conch overtook, salt and conch about equal 1920-1939, conch officially overtakes and continues to dominate today. Huge increase in catch by tons from 1950 to today

Lobster biology

Pelagic larvae, colonize down current environments, Pan-Caribbean theory (genetically, lobsters are one big family across the entire Caribbean), reproductive migration and aggregation, habitat requirements vary with age

Lobster biology role in management

Larvae drift for 6+ months so they go away and maybe other reef lobster larvae drift in, if “upstream” overfishes lobster no new babies in “downstream”, migrate to another location that may be out of protection zones or in another territory, need to manage multiple habitats

Threats to lobster fishery

Nurseries hurt by salinity changes, development, nutrient changes, hurricanes. Also disease (PaV1)

Casita pros and cons

CONS: Aggregate lobsters and single harvester could wipe them out quickly, easy spread of disease, casita can damage reefs if thrown around in hurricane

PROS: safer to freedive to, easy to harvest, create new habitat, less stress on lobsters

TCI lobster fishery and trends

Hand collected or pots and hooks, casitas began spring 2024, sold at processing plant.

Current regulations on lobster/conch

implementing total allowable catch, reducing vessels, closed season, reducing pots.

In TCI specifically: closed season, no SCUBA gear, export quota, TAC limit, closed areas, size limits

Lobster trends

Declining average tonnage per year. Also use of some illegal materials like bleaching, catching undersized lobsters

State of world fisheries and aquaculture (2024)

Since 1961, annual global growth in fish consumption has been twice as high as population growth

• demonstrates that the fisheries and aquaculture sector is crucial in meeting FAO’s goal of a world without hunger and malnutrition

Catch by gear type

~25 million tons from bottom trawling

~15 million tons from pelagic trawl

~20 million tons from purse seine

~18 million tons from small scale

~3 million tons from gillnet

~3 million tons from longline

~15 million tons from other gear

~10 million tons from unknown gear

Cod fishery example

Aquaculture trends over time compared to wild caught

Aquaculture now catches about the same tonnage as wild catch, used to be very little. We also consume 52% aquaculture caught fish (in 1968 it was 6%)

Stock status and trends

35.5% overfished/unsustainable, 64.5% sustainably fished. 77.2% of landings were from sustainably fished stocks. Effective management means better outcomes. Deep sea fisheries mostly overfished

Mislabeling seafood

Allows processors to avoid regulations and fees, or even to sneak illegally

caught fish into the supply chain. Mislabels on country of origin, species name, wild-caught or farmed.

Mislabeling can occur through

• Trans-shipping: when seafood products are exported through different countries to

avoid duties and tariffs

• At-sea transfers: when illegal fishing vessels transfer their catch to cargo vessels

carrying legitimately caught seafood

• Falsifying trade documents: Mislabeling seafood and concealing illegally caught fish evades inspection fees, permits, and other business costs that affect the price of responsibly caught seafood

Seafood fraud management

• Board vessels at sea

• Inspect processing plants

• Criminal and civil investigations

• Analytical tools like ELISA, NMR, stable isotopes

Case study on grouper fraud in TCI

Sold as grouper, but actually: 18% was actually grouper, 57% was catfish, and 25% snappers. Imported 78%, mislabeled 96% by origin or species.

LOCAL FISHERS ARE VICTIMS, not main source of mislabeling

Aquaculture definition

Cultivation of aquatic species in controlled aquatic environments, including marine and freshwater systems, to contribute to food security and conservation efforts.

Sustainable Development Goals (SDGs)

Adopted by UN in 2015, goal to end poverty and inequality and protect the planet. 3 Pillars of sustainable development: economic, social, environmental

Aquaculture and SDGs

Aquaculture supports hunger elimination, increasing sustainability of oceans, energy production potential

Aquaculture history

First saltwater aquaculture by Native Americans, first freshwater aquaculture in China, integrated agriculture-aquaculture systems develop, Europeans begin aquaculture and development continues, artificial breeding spread in the 1860s, artificial granulated food came in the 1950s.

Aquaculture System 1: Ponds (advantages and disadvantages)

Freshwater, brackish water, or saltwater.

Advantages: Can be low cost and environmentally friendly, better control over the culture environment (feeding, stocking density), rely on natural food sources in the pond

Disadvantages: deterioration of water quality due to high fish densities and waste accumulation, nutrient-enriched waste water can pollute surrounding ecosystems if not properly treated, vulnerable to flooding, may need to provide supplemental feed and management.

Aquaculture System 2: Cages (advantages and disadvantages)

In existing water bodies (Freshwater or marine), that allows free flow of water.

Advantages: Very diverse and flexibly used, high stocking density

Disadvantages: High environmental impact, vulnerable to storms, risk of fish escape, disease spread

Aquaculture System 3: Raceways (advantages and disadvantages)

Flow through system in an artificial channel. Oldest, most simple system in AQ. Used for species that need a constant water flow

Advantages: easy management, high density

Disadvantages: site-dependant (needs a flowing water source), waste water, fast disease spread

Aquaculture System 4: Recirculating Aquaculture Systems aka RAS (advantages and disadvantages)

Closed, land-based system

Advantages: Water is filtered and reused, reduces environmental impacts, ideal for urban and inland areas

Disadvantages: high tech and high experience needed, energy intensive

Species used in aquaculture and why

Carp, shrimps, prawns, catfish, tilapia, trouts, bass, abalone, salmon. High market demand, fast growth rates, and adaptability to controlled environments, or low-cost maintenance.

Can aquaculture be the future? Advantages, disadvantages

Overfished oceans will not produce enough seafood to feed the world in the long term, and most consumed fish are top predators (fishing down food web)

Advantages: Sustainable seafood production, improved job security, high income work, conserve ecosystems

Disadvantages: Environmental impacts, high food intake, disease outbreaks, limited freshwater resources

How biofloc (BFT) differs from trad. aquaculture

Differs from traditional aquaculture by utilizing beneficial microorganisms to convert fish waste into protein-rich food (floc) within a closed, high-density system. Also, uses settling tank compared to RAS filters.

How integrated multi-trophic aquaculture systems (IMTA) differs from trad. aquaculture

Very old, two or more organisms farmed together (polyculture), intentionally co-culturing species from different trophic levels fish, shellfish, and seaweed) to recycle waste nutrients into valuable products

How aquaponics differs from trad. aquaculture

Plant production AND fish production in symbiosis

Define invasive species

a non-native organism whose introduction causes or is likely to cause economic or environmental harm, or harm to human, animal, or plant health

Define non-native species

an organism, including its seeds, eggs, spores, or other biological material capable of propagating that species, that occurs outside of its natural range

Define endemic species

A biological taxon native to and restricted to a particular area or region and not found naturally anywhere else in the world

Define indigenous species

A biological taxon historically present in a particular area or region; can be found naturally in other areas

Invasive species natural introductions

wind, currents

Invasive species deliberate introduction

Agriculture, horticulture, aquaculture. Biological control. Releasing pets.

Invasive species accidental introduction

Travel (commercial shipping, drilling platforms, canals, recreational activities). Floating debris. Aquarium escapees.

Invasive species consequences

They cause ecosystem change in biodiversity and structure.

Invasive species detection: eDNA

Collect DNA from water, extract, PCR analysis. Two approaches: general primers → analyze overall biodiversity, OR species-specific primers → detect a particular target species.

Challenges for eDNA species-specific

Must design species-specific primers that work consistently in the target species, don’t amplify other species, and perform well with eDNA from water samples. Need a complete DNA database

High island endism and TCI endism

Islands are biodiversity hotspots, serious risk of extinctions. TCI: 6 endemic plant species, 7 endemic reptiles, etc.

TCI Australian Pine invasion

Introduced late 1800s for shade and wind breaks, Fast growth, flowers yearround, produces many seeds, is drought tolerant, displaces native vegetation with needles, has shallow roots that are easily uprooted and increase beach erosion

TCI Australian Pine control

Burning, manual removal, herbicide

TCI Lionfish invasion

Released into ocean off Florida in 1985, has spread across Gulf of Mexico, Caribbean, northeast US, and Central/South America

• South Caicos has some lionfish but relatively small abundance

Why are lionfish so successful

Habitat generalists (can live in many habitats), voracious feeder (outcompete native species), unique hunting technique (suction feeding), few known predators, fish naivety, parasite resistance, unusual shape and venom, year round reproduction (also 2.3 millions eggs/yr), and wide larval dispersal

Lionfish effects

Reduce fish recruitment, outcompete native species, impact ecosystem dynamics

Lionfish management

Lionfish culling (although neither frequent vs. infrequent culling regimes resulted in recovery of prey biomass) decreased density by 70%. Culled sites have higher colonization rates. Also promoting consumption, or reporting sightings to govt.

Define MPA

a space in the ocean where human activities are more strictly regulated than the surrounding waters - similar to parks we have on land

IUCN MPA Classifications

Category Ia: Strict nature reserve

Category Ib: Wilderness Area

Category II: National Park

Category III: Natural Monument

Category IV: Habitat/species management area

Category V: Protected landscape/seascape

Category VI: Managed Resource Protected Area

Why establish an MPA

Maintain or promote diversity, conserve or increase fish biomass and abundance, encourage emigration, “spill over”, export of eggs and larvae, conserve ecosystems, maintaining ecological processes, promote sustainable use, protect commercially valuable species

Conservation focus: Natural Heritage

Protecting natural biological communities, ecosystems and processes, as well as the ecosystem services they provide to current and future generations

Conservation focus: Cultural Heritage

Protecting submerged cultural resources that reflect maritime history and traditional connections to the sea

Conservation focus: Sustainable Production

Managing exploited species to support sustainable extraction of renewable living resources

TCI MPAs

Bell Sound National Park (used to be nature reserve but changed so Sailrock could use coastline/beaches), boiling hole, Admiral Cockburn Nature Reserve, and Admiral Cockburn National Park

How MPAs are managed: Multiple Use Marine area

allows for recreational use with some restrictions

How MPAs are managed: No Take Marine Areas

allows recreational activity but prohibits extraction/destruction to the area

How MPAs are managed: No Impact Marine Areas

allows recreational use but extraction, disposal of possible pollutants,

installation of materials, and disruption to the environment is not permitted

How MPAs are managed: No Access Marine Areas

no access of any sort to the area

MPA management times: Permanent, Conditional, Temporary

• Permanent: Protected indefinitely unless future legislation ends the protection

• Conditional: Potential to continue, reviewed periodically to see if it meets

objectives

• Temporary: Designed to meet short-term conservation goals

MPA Enforcement: Year Round, Seasonal, Rotating

• Year-round: enforcement on a permanent basis

-Such as marine sanctuaries, national parks, monuments

• Seasonal: Occasional enforcement during periods of sensitive ecological processes

-Such as during spawning, breeding or feeding

• Rotating: Cyclic enforcement at different times at different locations

- Used by areas aiming to achieve a short-term conservation goal

MPA effects on fisheries: spillover effect

Increase of the movement of fishes across reserve boundaries into adjacent fisheries. Increase of fish biomass, size, and larval production inside protected zones ends up spilling into surrounding fishing grounds and more fish for fishermen

MPA effects on fisheries: recruitment effect

Increase recruitment to non-reserve areas via larval dispersal. Boosts fisheries by protecting spawning stocks, which increases egg and larval production, leading to higher recruitment in adjacent fishing areas.

MPA spillover vs recruitment effect how to measure

Spillover: patterns of abundance or tag and release studies

Recruitment: egg and larval export modeling

Why focus on one more than the other (spillover or recruitment), depending on your conservation focus?

Spillover for smaller MPAs, rapid fishery benefits, fishermen (stakeholders) buy-in

Recruitment for ecosystem resilience and sustainability, species with long larval dispersal phases, regional or national scale management

Is a big MPA or a network of smaller ones better?

Depends on goal. Big MPA protects entire ecosystems and habitats in one place and is better for wide-ranging species, but spillover could be far from fishing communities and less flexibility if something goes wrong since whole ecosystem can be affected. Many small MPA enhances recruitment, likely covers more variety of habitats, more spillover opportunities across many locations, but harder to enforce and manage and they may not support large, mobile species

What role does CO2 play in climate change and fisheries?

Rising sea temperatures shift species distributions (often poleward), causes coral bleaching (loss of habitat), lowers pH

Climate change impacts on the ocean

Increased temperatures, reduced O2 availability, sea level rise, reduced ice cover, coral bleaching, ocean acidification, effects on fish growth, distribution, and behavior

Ocean acidification definition

decrease in ocean pH caused by the absorption of anthropogenic carbon dioxide (CO2) emissions

Ocean acidification ecological consequences

less carbonate for organisms like coral, conch, and crabs to use to build shells/skeletons, Phytoplankton and zooplankton also use calcium carbonate to build their shells so reduced calcification because less carbonate ions, lowered pH causes decreased metabolism and immune response, less resilient to climate change, increase molecular oxidative damage, and alter physiological stress response

Effects on fisheries: spawning/mismatch hypothesis

often temperature dependent, Shifts in time of spawning → shifts in distributions, higher mortality, maybe less food availability (mismatch hypothesis: changes in ocean chemistry can cause shifts in timing of food availability for larvae)

Effects on fisheries: larval survival and distribution

can be temperature dependent, changes in O2, salinity, and density reduces survival and/or limits growth, different species respond differently to environmental change since they have preferences, most common response is a change in spatial distribution (move to areas with more suitable conditions, like the poles)

Effects on fisheries: distribution patterns

Affected by food availability, temperature, light level, currents, predators, oxygen, water chemistry

Effects on fisheries: range shift

Straddling stocks (migrate between or inhabit both an EEZ and adjacent high seas areas) will move towards the high seas, most highly migratory stocks will move into the jurisdiction of new RFMOs, coastal states and RFMOs will be required to revise governance frameworks to support sustainable and equitable adaptation to shifting stocks, Mackerel Wars and the NEAFC

Catch potential with climate change and meaning for fisheries?

Increased catch in Arctic and sub-Arctic, decreased catch in Tropics, economic effects (fish price increase b/c reduced catches, demand decrease b/c of price), reducing potential for price increase, livelihoods of fisherman hurt

Adaptation/Mitigation/Challenges for fishing and management with climate change?

Adapt: changing fishing locations as stocks shift, adjust quotas, diversifying target species

Mitigate: lower CO2 emissions, sustainable fishing

Challenges: emissions pledges rolled back due to AI and political pressure, US withdrawal from the Paris Climate Agreement, EU's overall climate action is currently rated as "Insufficient" for meeting its target of a 55% reduction in emissions by 2030, primary climate change temperature threshold is 1.5°C (2.7°F) above pre-industrial levels and we have already exceeded this

Mitigate vs adapt definition

Mitigate: to make something less severe, actions that reduce damage

Adapt: to change or adjust something to suit new conditions

Hurricane overall impacts on biodiversity and human well being

Biodiversity: habitat destruction, erosion, sedimentation, change in species composition

Human well being: fishery collapse, houses destroyed, water borne diseases, agriculture loss, injuries and fatalities, community displacement

How do animals sense storm?

Fish sense storms using their swim bladder to detect rapid drops in barometric pressure

What are hurricane effects on fish spawning?

Strong currents and turbulence can displace or damage spawning grounds, destruction of coral reefs, seagrasses, and mangroves removes critical nursery areas, and eggs and larvae can be washed away, leading to reduced survival. Hurricanes can interrupt seasonal spawn, currents can transport larvae away from suitable nursery habitats, reducing recruitment success. Flooding can also cue spawning

What are hurricane effects on fish mortality?

Currents/waves can kill weaker fish, storm surge can wash fish into unsuitable habitats or strand them, habitat collapse