Fisheries and Climate Change

Fisheries and Climate Change
Pictured: Rutgers University Marine Field Station (RUMFS) Photo by Steve Luell Steve Luell AmeriCorps Watershed Ambassador WMA 14 – Mullica River

What is an Estuary? A partially enclosed coastal body of water where saltwater from the ocean mixes with freshwater from rivers, creeks and streams Sheltered from the full force of the waves and winds Important nurseries for many species of fish and shellfish Pictured: Great Bay, NJ looking toward Atlantic City Steve Luell

What are Ichthyoplankton?
Ichthyoplankton are larval fish found in the water column “Ichthyo” – fish “Plankton” – small organisms drifting or floating in the water Pictured: Cod (Gadus spp.) larvae

Why Sample Ichthyoplankton?
Evaluate recruitment success Recruitment refers to when juvenile fish survive to a size where they can be targeted by commercial and recreational fishermen Largely affected by mortality during the larval stages The recruitment success of many marine species depends on larval fish locating inlets and entering estuaries. The responses of larval fish to climate change and human factors such as pollution can also be observed by looking at when different species enter the estuary, the size of the larval fish, and the abundance of different species.

Ichthyoplankton Sampling
Sampling conducted weekly at Little Sheepshead Creek since 1989 During the night on the incoming tide Three consecutive 30 minute tows using a 1 mm mesh plankton net Sampling is conducted during the night because most larval fish prefer to travel under the cover of darkness to avoid predators.

Ultimate Bridgenetting
Route 37 Sampling sites for Ultimate Bridgenetting The red dots are new sites that have been added in “Ultimate Bridgenetting” is when multiple sites are sampled during the same night. This is typically done every two months. The samples collected from these sites have been found to have similar species diversity and abundance. Route 72

The rope is tied to the railing of the bridge using a bowline knot. This knot makes a sturdy loop that can support a tremendous amount of weight and can be untied easily afterward. A flow meter and a metal anchor are attached to the net and it is lowered into the water. Another flow meter is tied to the bridge using a bowline knot and lowered into the water next to the net. The flow meter measures the volume of water in each tow. Photos by Chris Filosa

After 30 minutes, the net is retrieved. Photos by Chris Filosa

The contents of the net are emptied into a bucket and will later be sorted at the field station. The numbers on the flow meters are recorded. After three 30 minute tows, the net is brought back to the field station and rinsed out into a bucket. The rinse is also sorted for larval fish. Photos by Chris Filosa

In addition to the flow meter (top left), temperature and salinity are also recorded. Salinity (the dissolved salt content in water) is measured using a refractometer (bottom left). Chris Filosa

Here is a copy of the datasheet that is filled out during this survey.

Samples preserved in 95% ethanol for later identification Preserved samples are sorted and identified to species using a dissecting microscope Chris Filosa

Summer Flounder (Paralichthys dentatus)
Examples of ichthyoplankton Flatfish metamorphose video:

Atlantic Menhaden (Brevoortia tyrannus)

Bay Anchovy (Anchoa mitchilli)

Killifish (Fundulus spp.)
Killifishes in the genus Fundulus include mummichog, banded killifish and striped killifish.

Hakes (Urophycis spp.) Urophycis is a genus of phycid hakes native to the Atlantic Ocean. Some species in this genus are spotted hake and red hake.

Drums and Croakers (Sciaenidae spp.)
Sciaenidae are a family of fish known as drum or croakers. They get their name from the sounds they produce with their swim bladders. Some common sciaenids include Atlantic croaker, spot, black drum, red drum and weakfish.

Horseshoe Crab (Limulus polyphemus)
Invertebrates are also frequently caught in the plankton net. Invertebrates are animals that lack backbones.

Other Invertebrates Pictured: Polychaete worm
Like earthworms and leeches, polychaetes are annelids (segmented worms). Unlike other worms, they have distinct heads with specialized sensory organs. They are an important part of the marine food web and are preyed upon by most fish and crustaceans. Over 10,000 species of polychaetes have been identified around the world thus far.

Other Invertebrates Pictured: Ephyra (free swimming precursor to the adult stage of a jellyfish, which is known as a “medusa”) There are several different phases in the life cycle of a jellyfish. The larvae, known as the planula, are covered with cilia which are fine hairlike organelles that are found on the surface of certain cells. The planula settle onto firm surfaces and become polyps. The polyp stage can last for many years. The polyp eventually metamorphose into an ephyra, which are able to swim. Eventually, the ephyra becomes a medusa, which is the adult stage of a jellyfish.

Other Invertebrates Pictured: Pea Crab
Pea crabs live inside oyster, clam and mussel shells where they feed on plankton and small particulates on the bivalves’ gills. Over time, they can cause damage to the gills of their hosts.

Other Invertebrates Pictured: Crabs – Megalopa (left) and Juvenile (right) The megalopa is the post larval stage in the life cycle of a crab. It is a voracious predator that feeds on zooplankton as it rides the currents. This stage typically only lasts for a week before it molts into a juvenile crab. Juvenile crabs are able to swim and walk, and they find shelter in grasses.

Other Invertebrates Pictured: Shrimp
Shrimp are crustaceans that are closely related to crabs, lobsters and crayfish. They have flexible abdomens with fanlike tails and swim backwards by rapidly flexing these features. There are over 2000 known species of shrimp found around the world.

Other Invertebrates Pictured: Squid
There are about 300 known species of squid around the world. They have special cells, called chromatophores, that enable it to change color to match it’s surroundings. Squids swim by jet propulsion. They suck water into their mantle (body cavity) and expel it through a siphon. They can move their siphon to change direction. They release ink when threatened to evade predators.

Sampling for Juveniles and Adults
Otter Trawling Gill Netting Beach Seining Wire Mesh “Killitraps” These are four common approaches for sampling juvenile and adult fish. An otter trawl is a cone shaped net that is towed behind a boat. With RUMFS surveys, the fish are identified to species, counted, and a subsample of 20 from each species are measured to the neared millimeter. Pictured is a deployed otter trawl. A gill net is a type of net that is suspended vertically in the water. Fish swim into it and become entangled in the mesh by the gills. Typically in RUMFS surveys, the nets are set for 60 minutes. The fish caught are identified, counted and measured. These two methods are used for sampling larger juveniles and adults. Chris Filosa

Killitrap Survey Six unbaited wire mesh “killitraps” deployed in the RUMFS boat basin Checked twice a week on Tuesdays and Fridays since 1990 Steve Luell

Seine Survey Joint collaboration between RUMFS and JCNERR
Two locations sampled once a month Graveling Point 1st Bridge on Great Bay Blvd 2012: August through October 2013 – Current: May through October JCNERR – Jacques Cousteau National Estuarine Research Reserve Steve Luell

Seine Survey Seine net is 20 feet wide with 4mm mesh
Net is deployed 80 feet off the beach and towed back to shore Three consecutive tows perpendicular to shore Steve Luell

Seine Survey Fish and predatory crabs (ex. blue crabs, spider crabs, calico crabs, green crabs) are identified and measured on site or back at RUMFS. Photos by Steve Luell

Northern and Southern Species
Northern species – center of distribution is north of the Middle Atlantic Bight Southern species – center of distribution is south of the Middle Atlantic Bight The Middle Atlantic Bight is between Cape Cod, MA and Cape Hatteras, NC. A bight is a curved feature in a coast. Distribution (or range) – the geographic area where a species naturally occurs Middle Atlantic Bight

95% of All Fish Caught American Eel (Anguilla rostrata)
Anchovies (Alosa spp.) Atlantic Croaker (Micropogonias undulatus) Atlantic Herring (Clupea harengus) Atlantic Menhaden (Brevoortia tyrannus) Gobies (Gobiosoma spp.) Northern Pipefish (Syngnathus fuscus) Sand Lances (Ammodytes spp.) Silversides (Menidia spp.) Summer Flounder (Paralichthys dentatus) Windowpane Flounder (Scophthalmus aquosus) Winter Flounder (Pseudopleuronectes americanus) Over 100 genera have been caught in the ichthyoplankton survey. 95% of the entire catch has been comprised of only 12 genera.

Atlantic Herring (Clupea harengus)
Spawns throughout the year with a peak in the fall Important forage for many species Filter feeders – feed entirely on plankton Form huge schools that can number in the hundreds of thousands One of the most commercially important species in the Northeast Northern Species Because of their schooling behavior and abundance, Atlantic herring are preyed upon by many species of predatory fish, marine birds and marine mammals such as whales, dolphins and seals. Atlantic herring are found throughout the North Atlantic. They range along the North American coast from southern Greenland to North Carolina, around Iceland, and along the European coast south to the Bay of Biscay (off the western coast of France). Atlantic herring are one of the most commercially important species in the Northeast. They are typically canned and sold as sardines and kippers. They are also used as bait for lobsters and tuna.

Sand Lance (Ammodytes spp.)
Important food source for many different species Burrow into sand to escape from predators Feed on zooplankton Spawning occurs in winter and spring Exact spawning locations are currently unknown Northern Species There are two species of sand lance found off NJ – American sand lance (Ammodytes americanus) and northern sand lance (A. dubius). American sand lances are typically found in bays and estuaries while northern sand lances live in deeper waters offshore. Steve Luell

Atlantic Cod (Gadus morhua)
Spawn from winter into early spring Females can produce up to 9 million eggs in a single spawning Live along the seafloor Prefer cold water and rocky substrate Feed on fish and invertebrates One of the most important commercial fisheries in the world Northern Species Atlantic cod are one of the top predators along the ocean bottom feeding on most fish and invertebrate species they encounter. Adult cod have few predators – sharks, seals and humans. Atlantic cod are found throughout the North Atlantic and into the Arctic Ocean. Their range extends along the North American coast from Greenland south to North Carolina, around Iceland, and along the European coast from the Barents Sea (off the northern coast of Norway and Russia) to the Bay of Biscay. Atlantic cod are one of the most important commercially harvested species in the world. Due to overfishing, the cod fishery in the northwestern Atlantic Ocean (off the Canadian Maritimes and New England) collapsed in the early 1990s and has yet to recover.

Atlantic Croaker (Micropogonias undulatus)
Spawn on the continental shelf from early September into late December in the Middle Atlantic Bight Feed on crustaceans, mollusks, worms. small fish and detritus Produce sounds using their swim bladder Live in bays and estuaries during spring and summer Migrate into coastal ocean in fall and winter In recent years, juveniles have been found overwintering in NJ estuaries Southern Species Detritus – dead and decomposing plant and animal matter Atlantic croaker get their name from the croaking noise they produce with their swim bladder.

Spot (Leiostomus xanthurus)
Spawn offshore from fall to early spring Most common between Chesapeake Bay and North Carolina Live in shallow bays and estuaries during summer Migrate into coastal ocean in fall and winter Northern populations migrate south for the winter Hampstead, NC honors the fish by holding the North Carolina Spot Festival every September Southern Species Chris Filosa

Black Drum (Pogonias cromis)
Spawns during the spring with a possibility of a secondary spawning in the fall Feed on mollusks, crustaceans, worms and occasionally small fish Chin barbels are used to locate prey on the bottom Use pharyngeal teeth in the back of their mouths to crush the shells of their prey Produce sounds using their swim bladder Can grow to more than 100 pounds Southern Species Black drum get their name from the sounds they produce using their swim bladder. The sounds produced by large schools of drum can sometimes be heard and even felt through the hull of a boat.

Northern Puffer (Sphoeroides maculatus)
Also known as blowfish Spawn from May to August Male guards the eggs until they hatch Southern Species Voracious predators Feed on small invertebrates including crabs, shrimp and worms Unlike tropical puffers, they are not poisonous When threatened, Northern puffers inflate themselves to deter predators by inhaling water or air into a special chamber near the stomach. Chris Filosa

Crevalle Jack (Caranx hippos)
Highly predatory – feed on fish and crustaceans Spawning occurs from March to September in subtropical waters Some larvae are carried northward by the Gulf Stream Use estuaries as nurseries - only found in NJ during summer Juveniles die off because of cold water temperatures in fall and winter Southern Species Chris Filosa

Pinfish (Lagodon rhomboides)
Voracious predators that feed on small invertebrates and fish eggs Adults also feed on plant matter Spawn offshore from October to March Abundant south of Virginia Use estuaries as nurseries - only found in NJ during summer Juveniles die off because of cold water temperatures in fall and winter Southern Species Chris Filosa

Summer Flounder (Paralichthys dentatus)
Highly valued commercially and recreationally Spawn on continental shelf from September through January Highly predatory and aggressive – they will even chase prey to the surface Eyes on left side of body Have large mouths with sharp teeth Also known as fluke Summer flounder are “left eyed” flounder. They migrate inshore to bays, estuaries and the coastal ocean in the summer, and offshore to deeper water during the winter.

Winter Flounder (Pseudopleuronectes americanus)
Spawn in bays and estuaries during winter and early spring Migrate to cooler, deeper waters offshore in the summer Eyes on right side of body Have small mouths and no teeth Feed on small invertebrates and plants Winter flounder are “right eyed” flounder. Winter flounder are highly valued commercially and recreationally. Chris Filosa

Hogchoker (Trinectes maculatus)
Found year round in estuaries Prefers sandy or muddy bottoms Feeds on worms, small crustaceans and insect larvae Spawns May to October Hogchokers received their unusual name because farmers years ago tried to feed these fish to their hogs. The hogs had a hard time swallowing this fish because of its bony body and rough scales. Hogchokers can tolerate a wide range of salinity. They can also be found in freshwater rivers and the coastal ocean. Chris Filosa

Bay Anchovy (Anchoa mitchilli)
One of the most abundant fish species in the Great Bay May be the most abundant fish species in the western North Atlantic Mainly feed on zooplankton Spawn from April to November Important food source for many different species Can tolerate a wide range of salinities Bay anchovies are preyed upon by many commercially and recreationally important species including weakfish, bluefish and striped bass. They can tolerate a wide range of salinities from freshwater to fully saline. Chris Filosa

Tautog (Tautoga onitis)
Also known as blackfish Spawn offshore and in estuaries from May to August Live near structures such as rocks, pilings and wrecks Feed on invertebrates, especially mussels, barnacles and crabs Use pharyngeal teeth in the back of their mouths to crush the shells of their prey The world record tautog was caught off Ocean City, NJ in January It weighed 25 lbs 0 oz. Chris Filosa

Oyster Toadfish (Opsanus tau)
Year round residents in estuaries Tolerant of polluted waters Spawn from April to August Males make a loud, foghorn like sound to attract mates Males guard the eggs until they hatch Aggressive predators Oyster toadfish lie on the bottom and ambush their prey as it swims by. Feed mostly on crabs and other crustaceans, but they also prey upon small fish and bivalves. They have powerful jaws that are used to crush shells. Chris Filosa

Spotted Hake (Urophycis regia)
Common from Cape Cod to Florida Spawn offshore from late summer into winter Most abundant in water 360 to 600 feet deep Juveniles enter estuaries Feed on crustaceans, squid and small fish Chris Filosa

Alewife (Alosa pseudoharengus)
One of two species of “river herring” Anadromous – live in the ocean but spawn in freshwater from April through June Adults migrate back to the ocean after spawning Juveniles migrate downstream to the ocean during late summer and fall Preferred bait for the spring lobster fishery in Maine The term “river herring” describes two species: blueback herring and alewives. Chris Filosa

American Eel (Anguilla rostrata)
Catadromous – Live in freshwater and spawn in saltwater Spawn in Sargasso Sea off coast of the Bahamas Most live for about 5 years but some can live for 15 to 20 years They can crawl across wet grass and through underground springs to get around obstructions American eels spawn in the Sargasso Sea off the coast of the Bahamas. The larvae drift in the ocean for 9 to 12 months before they become “glass eels”. The glass eels are carried by the Gulf Stream until they enter estuaries. Once they begin feeding, they develop pigment and become “elvers”. After several months, they grow into adults known as “yellow eels”. Chris Filosa

Mummichog (Fundulus heteroclitus)
Spawn early spring through summer during the full and new moon Feed on plant material, small invertebrates and small fish Extremely hardy Can consume over 2000 mosquito larvae in a day First fish in space – Skylab 3 in 1973 Mummichogs are important bait fish, they are preyed upon by most predators in the estuary. They are extremely hardy. Before the Clean Water Act was passed, mummichogs were the only fish species found in the severely polluted Hackensack River and Arthur Kill in New Jersey. They are used for natural mosquito control. One mummichog can consume over 2000 mosquito larvae in a single day. The mummichog became the first fish in space when several specimens were carried aboard the Skylab 3 mission for biological experiments in 1973. Chris Filosa

Also known as bunker Found from Nova Scotia to central Florida Spawn during fall into early winter in Middle Atlantic Bight Filter feeders – feed entirely on plankton Can filter 6 to 7 gallons of water per minute Important prey species Commercially important Spawning may occur year round depending on location. Limited spawning may take place in Middle Atlantic Bight coastal waters during the spring. Intense spawning takes place during the winter in the South Atlantic Bight. Menhaden are important prey for a variety of fish including bluefish, striped bass and sharks. Though they are not usually eaten by people, menhaden are a commercially important species. They are used to make fish oil, fertilizer and pet food. Menhaden are also popularly used as bait.

Crab Island Fish Factory Believed to have been founded by Joseph Wharton in the 1890’s Menhaden were processed to make fertilizer, animal feed, paint and even margarine Due to a crash in the menhaden fishery, the factory stopped operating in 1969 The factory was officially closed in 1973 The factory processed the menhaden into fish meal and oil. The fish oil was used to make paint in the United States and was exported to Germany and Canada to make margarine. About 1000 menhaden are needed to produce 20 gallons of fish oil. After the factory stopped operating in 1969, they kept a skeleton crew of eight people to maintain the grounds until 1973 in hopes that the menhaden population would rebound. Steve Luell

Horseshoe Crab (Limulus polyphemus)
Spawn along the water’s edge in May and June during the full and new moons Eggs are an important food source for migratory shore birds such as the red knot Feed on small clams, worms, crustaceans, and algae Considered “living fossils” Blue blood Harmless Pictured: Horseshoe crabs spawning at Graveling Point Even though they are not fish, horseshoe crabs are a common sight in NJ estuaries. Horseshoe crabs are not true crabs. They are more closely related to arachnids (ex. spiders, scorpions, ticks) than crustaceans. At least 11 species of migratory shore birds feed primarily on horseshoe crab eggs when they stopover in the Delaware Bay. The most famous is the red knot which winters in Tierra del Fuego at the southern most point in South America and migrates north to the arctic to breed. Horseshoe crabs are considered “living fossils” because they have remained relatively unchanged for almost 350 million years. Unlike humans who have hemoglobin in their blood, horseshoe crab blood uses hemocyanin to carry oxygen. Because hemocyanin contains copper, when the blood reacts with oxygen in the air, it turns blue. Even though it looks intimidating, the spike like tail (called a telson) is not dangerous. Horseshoe crabs use the telson to flip themselves over when they get pushed upside down. Steve Luell

Spawning Locations for Selected Estuarine Species in the Middle Atlantic Bight
Species that live in saltwater but migrate into freshwater to spawn are called “anadromous” fish. Examples of these are striped bass, river herring and American shad. Species that live in freshwater but migrate into saltwater to spawn are called “catadromous” fish. One well known example is the American eel, which spawns in the Sargasso Sea. Able, K.W., M.P. Fahay Ecology of Estuarine Fishes: Temperate Waters of the Western North Atlantic. John Hopkins Press

Minimum Weekly Winter Temperatures (Weeks 47-52 and 1-12)
Minimum weekly temperatures in Great Bay, NJ from 1976 to 2007. There have been fewer and shorter periods of freezing temperatures in recent years.

Species Diversity Species diversity has increased throughout the duration of the survey.

Contribution of Northern and Southern Species to this Analysis
Larval data from ichthyoplankton survey (1987 – 2006) Juvenile data from killitrap survey (1991 – 2006) For a majority of southern species, less than 10 individuals have been caught.

Weekly Abundance of Larval Fish at Little Egg Inlet, NJ
Larval data from ichthyoplankton survey (1987 – 2006) Solid line = Total Larvae Dotted line = Total larvae without anchovies (Anchoa spp.) Week 1 – First week of January Week 52 – Last week of December The amount of fish larvae caught is highest during the summer. The peaks in abundance from June to August are primarily the result of large collections of bay anchovies (Anchoa mitchilli) and other anchovy species. When anchovies are removed from this data, there are higher abundances of other larvae in the spring (between weeks 16 and 20, and week 24). The lowest collections of larval fish typically occur during the winter between January and March.

Monthly Abundance of Northern and Southern Larval Fishes
CPUE = Catch Per Unit Effort Larval data from ichthyoplankton survey (1987 – 2006) Southern larval fish are frequently caught during the late summer into fall with the peak being in September. Northern species are typically caught during the winter into spring.

Monthly Abundance of Northern and Southern Juvenile Fishes
CPUE = Catch Per Unit Effort Juvenile data from killitrap survey (1991 – 2006) Juveniles of northern species have been caught throughout the year in Great Bay, NJ. Southern juveniles are seen from summer into the fall but many die off because of cold water temperatures in the fall and winter.

Preliminary Findings Because of warming average annual temperatures:
Decrease in northern larvae entering Little Egg Inlet Increase in southern larvae entering Little Egg Inlet While a majority of the southern species that enter Little Egg Inlet do not survive the winter, several species have been found overwintering in Great Bay in recent years. If average annual temperatures continue to warm, more southern species will survive throughout the year which will completely alter fish communities in New Jersey estuaries.

Acknowledgements Special thanks are due to Dr. Ken Able, Roland Hagan, and the countless technicians, post-doctoral fellows, graduate students, summer interns, and volunteers at RUMFS, Melanie Reding, Kim Capone and the volunteers at JCNERR, and Chris Filosa for allowing me use his pictures.

Acknowledgements All graphs from:
Able, K.W., M.P. Fahay Ecology of Estuarine Fishes: Temperate Waters of the Western North Atlantic. John Hopkins Press

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