Fundamentals Marine Fisheries Midterm

Systematics/Taxonomy

study of the diversity, relationships, and evolution of organisms and how to put names on them

Fisheries

Study related to human use of aquatic organisms

Catch

total number of organisms caught

Target catch

number of intended targets caught

Incidental/Bycatch

number of unintended organisms caught

Discards

The organisms you don’t keep

Landings

Number of fish kept and brought to port

Effort

Time spent fishing and the resources used in the process

Catch Per Unit Effort (CPUE)

Fish caught in a chunk of time

Catchability Coefficient (q)

the relationship between the catch rate and the true population size

Stock

a population of fish within a certain area that can reproduce and sustain itself

Recruitment

the addition of new individuals to a fish stock through reproduction or immigration

Cohort

a group of fish born in the same year or season, often used in population studies to assess growth and survival

Fishery Dependent Data

data collected from fishing activities that provide information on stock status and catch rates

Fishery independent data

data collected through scientific surveys and assessments that do not rely on commercial fishing activities, used to estimate fish populations and ecosystem health

Carrying capacity

the maximum number of individuals that an environment can sustain without negative effects on the ecosystem

Maximum sustainable yield

highest theoretical yield that can be continuously taken (on average) from stock under existing environmental conditions without significantly affecting the reproduction process

Overfished

A stock exploited to a degree that there reproduction and MSY is jeopardized

Overfishing

A stock having a higher harvest rate than rate that produces its MSY

Kobe Plot

Upwelling

A spatially and temporally limited movement of nutrient-rich, cooler waters into the euphotic zone. 25% of fisheries catch comes form 5 upwellings that are 5% of the oceans surface

Types of upwelling

wind induced (gulf of Panama), island or seamount (Galapagos), wind/current (eastern boundary currents), monsoonal (somali), equitorial divergence, divergence of open ocean or currents

Primary production

heterogeneous in space and time, requires sunlight, requires nutrients. Photosynthetic organisms are the base of food webs

North Atlantic Spring Bloom

Clupeoid fishes

Herrings, anchovies, shads, sardines, pilchards, menhaden. Synapomorphies: scutes, swim bladder connections. Life history characteristics: rapid growth, short lived, early maturity, high fecundity, schoolers, pop size can vary greatly. Often boom and bust fisheries.

Passive Gear

Target species move to the gear. E.g. gill nets, long line, fyke and pound nets, traps, pots

Active Gear

Gear that is moved to the target species (propelling or towing). Trawls, dredged, harpoons

Demersal Fisheries

Multi-species fisheries, bottom associated, in waters over the continental shelf, often 20+ species vulnerable to the fishing gear, can assess but not manage stocks/species individually

Gadiformes

Cods, hakes, grenadiers. Earlyish maturation, high fecundity, schoolers.

Atlantic Cod fishery

Super old. Collapsed hard in the 70s. Whoopsies

Hypotheses for Atlantic Cod Fishery Collapse

overfishing and slow govt response, ability to catch fish efficiently at low abundance, failure to recognize spawn/recruit relationship, lack of accounting to increasing efficiency of effort, increased discarding and non reporting of small fish, overestimates of stockproductivites/underestimates of fishing mortality

Pelagic fishes biological characteristics

Most are top level predators, feed on smaller fishes and squids, high metabolic rates, several species maintain elevated temperatures in some body regions

Pelagic fishes (minus sharks) life history characteristics

High fecundity, broadcast spawning over large geographic area, rapid growth, most species reach sexual maturity at 2-4 years, can be relatively long lived (6-20+)

Major pelagic species

Tunas, wahoo swordfish, billfishes, scimbriformes, mahi mahi, lamnidae, carcharhinidae

Atlantic bluefin tuna fishery

centuries old, rapid buildup of overfishing, major reforms in 2010

Growth overfishing

When fish are harvested before they reach the size where yield per recruit is optimized

Deepsea Fisheries and Shark Fisheries

long lived, slow growing, late age at maturity, low fecundity, typically boom and bust due to mismanagement, more like mining (exploit and move on)

Orange Roughy Biology

generalist body form, slow growing, old at first maturity, max age 100+, winter spawning aggregations around seamounts, low fecundity, single batch spawners,

Sharks and Rays biology

1000+ species, slow growing maturity at 15+, low fecundity (1 or 2 year reproductive cycles, few pups per cycle), long lived 25+

US Shark Fisheries

Small until 1970s then got big, fins highly valued, quickly became overfished, shark finning banned in US

General status of stocks for Shark fisheries

landing records not good, many species with greatly reduced biomass, very long rebuild time

Chesapeake Bay Fishes

~350 species, freshwater to marine habitats, tolerant of wide range of temperature and salinities, many transient species, many are commercially and recreationally important

Take homes from the 202 ASMFC stock assessment

Adult mortality for coastline metapopulation unknown, juvenile mortality unknown for all systems, coastwide metapopulation considered depleted based on the decline in coastwide landings

American Shad age shift

1998-2005 age 5 most abundant, increase in average age due to increase in older individuals

2016-2021 average age increases because decrease in age 5s

Blue Catfish

Invasive. 2011 Resolution of the Atlantic States Marine Fisheries Commission: potential negative effects on other managed species. All practicable efforts should be made to reduce population levels and ranges of invasive blue catifsh

Eastern Oyster biology

bivalve mollusk, feeds on phytoplankton, aggregate to form reef structure, grow to ~20cm, max age 20-25 years, broad environmental tolerance, protandric hermaphrodites, mature age 1, spawn late spring through early fall, female fecundity 20-30 million per spawn

Eastern oyster fishery

Large in 1800s through mid 1900s, overfishing as far back as late 1800s, patent tongs hand tongs and oyster dredge common, fishery decimated by diseases (MSX and Dermo)

Haplosporidium nelsoni

Parasitic protist agent of MSX, known since 1959 in Chesapeake bay, likely introduce from pacific oyster shipments, not directly transmissible among oysters

Perkinsus marinus

agent of dermo, basal dinoflagellate, known since 1940s in Chesapeake, directly transmissible among oysters,

Oyster Management today — Public Grounds

annual estimates of abundance of oysters, license limit, rotational harvest + shell repletion, gear type and time restricitons, oyster sanctuaries, restoration to increase footprint of extant reefs with alternate substrates, Stock Management Advisory Committee

Oyster management today - private grounds

Traditional culture menthods, spat on shell, increased interest in containerized aquacultre

Eastern Oyster fishery since 2000s

Increase in catch, oysters developed tolerance to perkinsus, increased recruitment ~2008, rotational harvests implemented in 2007. Biggest impediment — oysters living less long, not contributing to shell base as much, illegal harvesting more prevalent

Sea scallop biology

20-120meters, max age ~20 years, max size ~9 inch shell height, Planktonic then settlement life phase, separate sexes, females mature in 1st or 2nd year, spawn in fall, George’s bank gyre entrains larvae, juveniles mobile adults not as much, fast growing

Sea scallop fishery

Most valuable wild scallop fishery, was most valuable fishery in VA, most valuable single species in US in 2007, major gear scallop dredge

Scallop fishery management

Overfished in 1990s, limited access program implementd in 1994, effort reduction, limitations on crew size, gear restrictions (increase in cull ring size). Part of annual catch contributes to the Research Set Aside, money from RSA used to fund research. money also set aside to fund Observer program

Sea scallop closed area rotational management

Implemented 2004, elephant trunk was first area closed, closure protected 2 massive year classes, remained closed for 3 years then controlled re opening

Blue crab biology

Western atlantic, tolerate wide range of temperatures, prefer estuarine salinities, eat bivalves shrimp plant matter detritus etc, important prey and predator, relatively short lived ~2 or ~3 years

Blue crab life cycles

lots of stages, both in bay and open ocean. mating occurs may to october in brackish water. females store spermatophores

Blue Crab Fishery

Chesapeake bay with 1/3rd of US blue crab catch, pot fishery, winter dredge fishery (current moratorium), peeler crab/soft shelled crab fishery, recreational fishery.

Blue crab management

minimum size, limited entry implemented in 2008, effort reduction. Spawning sanctuary. Chesapeake bay stock assessment committee uses VIMS winter dredge survey as indicator of stock status.

Blue crab stock status

in 2024 evaluated to NOT be overfished. However, low recruitment and high male exploitation still concerning. Continued precautionary management recommended