Northern shrimp ( (Clark, et al., 2000; Haynes, 1979; Haynes and Wigley, 1969; Koeller, 2006; Morrier and Harvey, 2003; "Northern shrimp research in the Northern Atlantic", 1997; Storm and Pederson, 2003)) are commonly found in the northeastern part of Nearctic region of the North Atlantic Ocean and in the North Pacific Ocean off the coasts of British Columbia and eastern Russia. The Gulf of Maine, Gulf of Labrador, and northward to Davis Strait (between Greenland and Canada) have been reported to contain northern shrimp as well as the Denmark Strait (between Greenland and Iceland) and the Greenland Sea. In the Norwegian regions (northern Palearctic region), northern shrimp inhabit the Barents Sea, Norwegian Sea, and the North Sea.
Northern shrimp inhabit marine environments in polar shallows along the coast. They can most commonly be found in colder waters (2 °C- 6 °C) and can withstand water as cold as -1 °C. In the Gulf of Maine, the shallow sea floor is composed of mud and fine sand. It is most common to find the shrimp in depths as shallow as 100m and as deep as 600m. Northern shrimp cluster towards the muddy floors as it is a more suitable place to breed and spawn their eggs. They live in the shallow inshore for 1-2 years on the sea floor and then move towards the deeper waters after molting 5 or 6 times. These deeper environments tend to be colder from where they spawned and have a sandier sea floor. (Clark, et al., 2000; Koeller, 2006; "Northern shrimp research in the Northern Atlantic", 1997; Taggart, et al., 1995; Wieland and Siegstad, 2012)
At hatching, all larvae are males, progressing through six stages as larvae. In these first six stages, they measure from 6mm to 20mm total length after molting 5 or 6 times. Their bodies are semi-translucent with an orange hue. When they reach the seventh and eighth stage, they are considered juveniles. They grow in length to 15mm to 21mm, and their colors become more vivid. After that stage they are considered adult males. Northern shrimp are ectothermic and require heat from their surroundings to regulate their body temperature.
Males undergo a sexual transformation to females, growing two or three times larger and develop reproductive organs to carry eggs. The sex change occurs 1-5 years after hatching depending on the geographic location of the shrimp. In the Barents Sea, it is more common to see the sex change happen later in life (5 years) compared to the Gulf of Maine (ca. 1 year).
Because of this sequential hermaphroditism, males are significantly smaller than females. Males average 120mm long and weigh ca. 2g, while females reach lengths of 180mm and weigh as much as 3g. Males have white and orange stripes, while females are entirely light orange. (Bergström, 1992; Koeller, 2006; Ouellet and Allard, 2006; Storm and Pederson, 2003; Taggart, et al., 1995)
Female northern shrimp carry their unfertilized eggs for up to eight months before fertilizing them with stored sperm and releasing the eggs. They spawn in the shallow coasts. All larvae are considered male and measure at least 6mm long. As larvae, the shrimp grow in stages determined by molts. Larval shrimp go through six molts, and, on the seventh molt, they are considered juveniles, measuring at ca. 18.4mm in length (range 16 to 21mm). During each molt the shrimp develop teeth, appendages (pereopods), and more segmentation (telson). Larval stages are more intense and rapid than the juvenile stages as they are developing larger parts of their body at quicker rates (every 1 to 2 weeks). Northern shrimp develop reproductive organs during juvenile molts. At this point, the shrimp are considered adult males and will reproduce once or twice before molting for one last time. The males average 120mm long. These shrimp transition to females, which can take up to several weeks and molts to complete. The females average lengths of 180mm and grow indeterminately. (Bergström, 1992; Haynes, 1979; Koeller, 2006; Storm and Pederson, 2003; "Synopsis of biological data on the pink shrimp, Pandalus borealis", 1985)
Female and male northern shrimp breed once annually from July through September and the females lay their eggs from March to May. It is unknown whether females stay with their mate after breeding. The precursor for females is a final molt before they are approached by males to breed. There are pheromones released by males before mounting the back of the female to signal they are ready to breed. Their mating system has not been documented. ("Synopsis of biological data on the pink shrimp, Pandalus borealis", 1985; Tricarico and Aquiloni, 2015)
Northern shrimp breed annually from July through September. The females are oviparous, carrying their eggs and the stored sperm for up to eight months before fertilizing them. While carrying the eggs and sperm, the eggs are resting between their pleopods. The eggs are externally visible on the shrimp. Once the eggs hatch, all larvae are considered males. The time to independence is 0 minutes, as the young are immediately independent. Birth mass has not been reported.
These shrimp are protandrous; as males mature, they transition to females. Females can reproduce right after transitioning, starting as early as 12 months of age (though it varies regionally, and can take up to 5 years), and will continue to reproduce until their life ends. Males can reproduce at about four months of age, between their seventh and eighth molt and before they transition to females. The number of eggs carried by the female is dependent on their size but can range from 600 to 4,900 eggs with the average of 2,000. The average period during which females carry their unfertilized eggs is ca. 164 days. (Dodson, et al., 2005; "Synopsis of biological data on the pink shrimp, Pandalus borealis", 1985; Tricarico and Aquiloni, 2015)
Female northern shrimp carry their unfertilized eggs and stored sperm externally for up to eight months before the eggs are fertilized and laid. Males provide no parental investment beyond the act of mating. ("Synopsis of biological data on the pink shrimp, Pandalus borealis", 1985)
Northern shrimp live up to a year (as males) before transitioning into females. As females, they live up to 7 more years in the wild. The shrimp are kept in captivity as long as it takes to transport them to markets, restaurants or preparation locations. In the wild, northern shrimp are stressed by trawls and predation, which can shorten their lifespan. (Kennedy, et al., 2013; "Synopsis of biological data on the pink shrimp, Pandalus borealis", 1985)
While the behavior of northern shrimp is not well-studied, they are known to use olfactory contact and some visual signals with conspecifics. Northern shrimp can also release pheromones that other northern shrimp can pick up, sending signals such as readiness to breed. Schooling in northern shrimp is dense and is determined by size of the shrimp. Females and males tend to school in dense patches near inshore beds during the breeding season. They are motile and social in their regions.
Migration occurs horizontally and vertically inshore. Horizontal migration occurs because of oceanic currents and mating. Vertical migration occurs because the females tend to stay near the seabed when egg-laying. As shrimp forage for food at greater depths during the day, migration also occurs daily. These shrimp are diurnal and feed more during the day rather than at night. (Bergström, 1992; Haynes, 1979; Jónsdóttir, 2013; Jónsdóttir, 2017; "Synopsis of biological data on the pink shrimp, Pandalus borealis", 1985; Tricarico and Aquiloni, 2015)
Home range has not been reported for these shrimp. Northern shrimp stay close to where they are spawned and are mostly sedentary. They do not defend a territory. ("Synopsis of biological data on the pink shrimp, Pandalus borealis", 1985; Tricarico and Aquiloni, 2015)
Northern shrimp have light adapting hormones that allow their eyes to see in brighter conditions. Not much is known about how northern shrimp can see, but most shrimp use either polarized light or movement detection. Mantis shrimp (Gonodactylaceus falcatus) use polarized light to communicate with each other. It is a type of communication signal used between this species and other shrimp species. It can be used to detect predators in the area, parasites, and even rivals. Goby shrimp (Psilogobius mainlandi) use their antennae and front legs to push one another to signal their presence. (Ferlund, 1976; Marshall, et al., 2015; Preston, 1978)
Phytoplankton are the main source of food for the larval and juvenile stages for these filter-feeding northern shrimp. Ariza and Ouellet (2009) examined the stomach contents of 30 northern shrimp larvae. They found that 50% of contents (by volume) were phytoplankton and the rest consisted of parts of zooplankton and particles from minerals. As the shrimp enter the adult stage, their diet consists of large diatoms and zooplankton, but majority of what they consume is phytoplankton. Phytoplankton still make up more than half of their diet because of this food item's availability. (Ariza and Ouellet, 2009; Lin, et al., 2008; Storm and Pederson, 2003; Wieland and Siegstad, 2012)
The main predators of northern shrimp are humans (Homo sapiens). Northern shrimp are the most common type of shrimp consumed by humans and are often captured with large cone-shaped nets. Octopi and seals may also feed on them. Atlantic cod (Gadus morhua) and silver hake (Merluccius bilinearis) consume northern shrimp opportunistically, but the impact of humans as predators is more substantial. (Haynes, 1979; Jónsdóttir, 2013; Jónsdóttir, 2017; "Synopsis of biological data on the pink shrimp, Pandalus borealis", 1985)
Northern shrimp consume plankton and other micro-organisms. They are consumed by many fish, octopi, and seals; however, humans are the primary consumer.
Northern shrimp are hosts for internal parasites that include isopods (Proboyrus buitendijki, Bopyroides hyppolytes, Hemiarthrus abdominalis), an apostome ciliate (Gymnodinioides paciﬁca), and a crustacean parasite from the class Thecostraca (Sylon hippolytes). ("Synopsis of biological data on the pink shrimp, Pandalus borealis", 1985)
Northern shrimp are a common food served in restaurants and offered for purchase in stores. Commercial fishing provides a majority of the shrimp seen in stores and restaurants.
In 2005-2006, Maine fisheries harvested roughly 2000 metric tons of northern shrimp. Annual profits at this time averaged $6 million. Currently, the stocks in the Gulf of Maine have been depleted and fishing is prohibited until 2024. ("ASMFC northern shrimp section extends moratorium on commercial and recreational fishing through 2024", 2021; "Northern shrimp research in the Northern Atlantic", 1997)
There are no known adverse economic effects of northern shrimp on humans.
Northern shrimp have no special status on CITES appendices, the State of Michigan List and the United States Endangered Species Act List. Northern shrimp have not been evaluated on the IUCN Red List.
Ocean warming impacts the populations of northern shrimp. Trawling accounts for the abundance of catches, and poorly-regulated harvesting by humans is a major threat. Even if individuals are not caught by trawling, it causes stress to the remaining shrimp populations and can cause them to die before reaching full maturity.
Conservation efforts are being made by Atlantic States Marine Fisheries Commission (ASMFC) in the north Atlantic Ocean. Because the Gulf of Maine accounts for the most catches in the U.S., restrictions have been put in place to conserve the current population. In 2010, the yearly seasonal catch from the Gulf of Maine averaged 6000 metric tons of shrimp. In 2014, the decline in populations of northern shrimp caused the number to fall to under 500 metric tons. This led ASMFC to prohibit all fishing of northern shrimp until 2024 in the Gulf of Maine until populations remain steady. ("ASMFC northern shrimp section extends moratorium on commercial and recreational fishing through 2024", 2021)
Daphne Sturniolo (author), Radford University, Sierra Felty (editor), Radford University, Bianca Plowman (editor), Radford University, Karen Powers (editor), Radford University, Victoria Raulerson (editor), Radford University, Christopher Wozniak (editor), Radford University, Genevieve Barnett (editor), Colorado State University.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
uses smells or other chemicals to communicate
the nearshore aquatic habitats near a coast, or shoreline.
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
fertilization takes place outside the female's body
parental care is carried out by females
union of egg and spermatozoan
a method of feeding where small food particles are filtered from the surrounding water by various mechanisms. Used mainly by aquatic invertebrates, especially plankton, but also by baleen whales.
A substance that provides both nutrients and energy to a living thing.
Animals with indeterminate growth continue to grow throughout their lives.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
makes seasonal movements between breeding and wintering grounds
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
chemicals released into air or water that are detected by and responded to by other animals of the same species
photosynthetic or plant constituent of plankton; mainly unicellular algae. (Compare to zooplankton.)
an animal that mainly eats plankton
the regions of the earth that surround the north and south poles, from the north pole to 60 degrees north and from the south pole to 60 degrees south.
light waves that are oriented in particular direction. For example, light reflected off of water has waves vibrating horizontally. Some animals, such as bees, can detect which way light is polarized and use that information. People cannot, unless they use special equipment.
condition of hermaphroditic animals (and plants) in which the male organs and their products appear before the female organs and their products
mainly lives in oceans, seas, or other bodies of salt water.
breeding is confined to a particular season
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
associates with others of its species; forms social groups.
mature spermatozoa are stored by females following copulation. Male sperm storage also occurs, as sperm are retained in the male epididymes (in mammals) for a period that can, in some cases, extend over several weeks or more, but here we use the term to refer only to sperm storage by females.
uses touch to communicate
uses sight to communicate
animal constituent of plankton; mainly small crustaceans and fish larvae. (Compare to phytoplankton.)
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