Preventing Extinctions cover

Preventing Extinctions


Understanding the threats endangered species face and lessons learned from the past can help us determine how best to avoid future extinctions.
What factors lead to a species being listed as endangered? Let's use the Aquarium of the Pacific’s Horses and Dragons and Vanishing Animals exhibits as a jumping-off point, and learn about the factors that cause extinctions and current threats to endangered species.
Aquarium of the Pacific

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Preventing Extinctions

Habitat Loss

Degradation, fragmentation, and destruction of natural habitat are major threats to many animal species, and they can be traced to human activity. Diversion and pollution of water, logging and agricultural activity, climate change as a result of the burning of fossil fuels, and other evidence of the expanding human footprint all contribute to habitat loss.

This leads to overcrowding and increased competition among the resident plants and animals in the ecosystem and can also create problems for migratory and territorial animals.


Heather Dine


Many of the animals featured in the Horses and Dragons exhibits, syngnathids, rely on seagrass beds as habitat. Boats and trawlers can cause fragmentation of seagrass beds where seahorses live.

These animals are particularly vulnerable because they are slow swimmers and can’t get out of the path of boats and trawlers. Also, because seahorses are monogamous during the breeding season, the loss of a single seahorse can drastically reduce reproductive rates.

Infrastructure like roads, dams, and other development causes habitat fragmentation. Freshwater streams, represented in the Vanishing Animals gallery, serve as corridors for fish and migrating wildlife and are particularly important in connecting fragmented habitats.

California Tiger Salamander

Johnny Eckler/ USFWS

California Tiger Salamander

Newts and salamanders in these habitats are impacted by fragmentation.

In places where existing infrastructure has fragmented a habitat, local governments can help endangered species by protecting or creating new pathways for them to travel.

In the Bay Area, officials close a stretch of road through a local park for four months to protect native California newts during their breeding and migration season.

In Sonoma County, officials built tunnels under roads giving the salamanders access to ponds where they breed, and students at the local university are helping to divert the salamanders into the tunnels.

Overhunting and Overfishing

Overhunting and overfishing occur when a species is removed from an ecosystem too quickly for it to reproduce and replace itself. These issues affect several of the species on display in the Horses and Dragons and Vanishing Animals exhibits.

Atlantic cod is a fish species that was once abundant throughout the northern Atlantic Ocean. On view in the Vanishing Animals gallery, they have been fished to the point of commercial extinction in North America. As stocks declined, Canada declared a moratorium on cod fishing, which may eventually lead to their recovery.

Atlantic Cod

Joachim S. Müller

Atlantic Cod

Atlantic cod still exist in the wild, but there are not enough to support the commercial fishery.

Cardinal Tetra Fish

Vinny DiDuca/Project Piaba

Cardinal Tetra Fish

There are also success stories in the Vanishing Animals gallery that give examples of measures we can take to help overfished and overhunted species rebound. An exhibit housing cardinal tetras and discus fish tells the story of how these species, which were once overharvested for the home aquarium trade, are now a renewable resource and job creator for Brazilian fishermen.

Project Piaba is an organization that manages the fishery sustainably. Maintaining the cardinal tetra fishery supports local communities while enhancing the conservation of one of the world’s most biodiverse ecosystems.

The coral exhibit in the Vanishing Animals gallery demonstrates the effect of overfishing on coral reefs. Grazing fish keep the algae in check, preventing overgrowth on the coral. When too many of these fish are removed, algae can over - whelm the coral. This is further exacerbated by fertilizers in agricultural runoff. Overfishing is a major contributing factor to the decline in coral reefs since the 1970s.

Harmful fishing practices also pose a threat. For example, about 2 million seahorses are removed from their habitats each year as accidental bycatch by boats trawling for shrimp.

Aquarium visitors can learn about aquaculture as a sustainable source of environmentally responsible seafood in the Vanishing Animals gallery. Sourcing our seafood from aquaculture farms would help circumvent the harmful fishing practices and overfishing currently impacting commercial fisheries, allowing wild fish populations to recover.


Diseases affecting plants and animals pose threats to endangered species and in recent years have led to mass extinctions. Healthy ecosystems have evolved defenses against disease, but the introduction of invasive species and weakening of ecosystem health due to factors like climate change and habitat loss make populations more vulnerable to disease.

Sea star wasting disease caused a massive die-off of sea stars along the West Coast in 2013 and 2014. Scientists have since found a virus to be the potential cause and rising ocean water temperatures a potential trigger. Juvenile sea star populations in many places began to rebound in 2015.


Aquarium of the Pacific


Outbreaks occurred previously in the 1970s and 1980s, but this bout is thought to have been more widespread and virulent due to the warmer waters attributed to El Niño and “The Blob,” an area of warmer water that persisted off the West Coast in 2013 and 2014. Climate change will continue to increase ocean temperatures, making more marine life vulnerable to the spread of disease.

Chytridiomycosis is a skin disease caused by a virus affecting 30 percent of world’s amphibian species. It has been found in wild and captive populations of amphibians on every amphibian-inhabited continent. Although the source of the virus has not been determined definitively, it is thought to have originated with global trade of amphibians for food, laboratory animals, and pets.

Scientists are searching for ways to treat chytridiomycosis, including antifungal baths and thermal treatments for tadpoles. These treatments could help prevent local extinctions of amphibian species, like those found in the freshwater stream habitat in the Vanishing Animals gallery.

Invasive Species

Invasive species are those that are not native to the ecosystem where they have been introduced and whose presence is likely to cause harm by outcompeting native species for resources, hybridizing with native species, or preying on native species.

In the Vanishing Animals gallery, several invasive species are on display in the freshwater stream exhibit, including fish species like bluegill, black crappie, and largemouth bass; Louisiana crayfish; and the eastern tiger salamander.

Crayfish are believed to have been introduced to California waterways more than a century ago to be used as bait for fishing. Voracious predators, crayfish have had a destructive impact on native amphibians like the California newt and California tree frog, now both listed as threatened.

Groups like the Mountains Restoration Trust are working to remove crayfish from local creeks and streams to help native species rebound. The crayfish they catch with nets and buckets are frozen and fed to animals like raccoons and opossums being rehabilitated at wildlife centers.

Morgan Evans

The non-native eastern tiger salamander is interbreeding with the native California tiger salamander, creating what scientists call a super hybrid that is more likely to survive than either of its parent species. It is wiping out food sources and outcompeting the native species, which could have far-reaching impacts on the ecosystems where it is thriving.

The public can help stop the spread of invasive species. Never release an animal into the wild, and follow fishing and boating regulations carefully.

Be sure to disinfect boats and gear before moving from one waterway to another to prevent the accidental transport of invasive species. If you own a home aquarium, only purchase aquarium animals from reputable sellers and follow state regulations for prohibited species.


Pollution is a major factor affecting the health of marine ecosystems. In addition to trash and debris and accidents like oil spills, pollution also comes from runoff entering waterways carrying soil, pesticides, fertilizers, oil, toxic chemicals, and other pollutants or from sediment flowing into rivers due to agriculture, construction, or logging.

The animals in the freshwater stream exhibit in the Vanishing Animals gallery are impacted by these types of pollution. These pollutants enter streams and rivers when irrigation is not properly managed or during rainstorms and as snow melts. It then can travel downstream to the ocean, where it can cause algal blooms and produce dead zones deprived of oxygen.


Andrew Reitsma


Waterways in the Amazon, like those where cardinal tetras and discus are harvested, are impacted by sediment flowing into rivers from logging.

Project Piaba provides employment for the fishermen it works with, who would otherwise be forced to turn to environmentally damaging jobs like logging, cattle ranching, and gold mining.

The public can help prevent this type of pollution by controlling soil erosion in your home landscaping, keeping litter out of streets and gutters, safely disposing of household chemicals, avoiding the use of herbicides and pesticides, and maintaining septic systems properly.

Climate Change

Climate change resulting from human activity is a major threat to coral reefs. A warming ocean and ocean acidification will make it harder for corals to survive, which will have a ripple effect on the millions of species that rely on coral reefs. At the Aquarium, live corals are now on view in the Tropical Pacific Preview exhibit on the first floor, in the Tropical Pacific Gallery, and in the Vanishing Animals gallery.

Reef-building corals depend on algae called zooxanthellae living in their tissues to provide the nutrients they need to grow and survive. Corals return the favor by providing the algae with a safe place to live.

To maintain healthy algae, a coral reef needs sunlight, clean water, a water temperature of 68° to 90°F, space to grow, and an adequate population of reef fish to inhibit the overgrowth of algae by feeding on it. Changes in these environmental conditions can cause the reef to become stressed and bleached due to loss of its zooxanthellae.

According to a recent report by the World Resources Institute (WRI), 75 percent of the world’s coral reefs are at risk from local and global stresses. Ten percent of coral reefs have already been damaged beyond repair. If we do not change our ways, WRI projects that 90 percent of coral reefs will be in danger by 2030, and all will be by 2050.

USFWS/Rick Kuyper

We must slow the rate of climate change and mitigate its impacts to help preserve coral reefs, as well as other marine and terrestrial environments that are vulnerable.


Many approaches have been developed to protect endangered animals, give species a chance to increase their populations, and ultimately prevent extinctions. Zoos and aquariums have created Species Survival Plans (SSPs) to manage breeding of endangered species and in some cases look for ways to reintroduce these animals into the wild.

The successful reintroduction of California Condors back into the wild and recovery of the American alligator are examples that give hope for many species facing extinction.


Robin Riggs


The Aquarium of the Pacific participates in several SSPs for endangered species like abalone, Guam Kingfishers, and Magellanic Penguins.

Governments at the local, state, and federal levels can support endangered species by directing funding toward research and monitoring and by designating protected spaces for ecosystems to recover.

These can include marine protected areas, which serve as safe havens for marine life by restricting human activity for conservation purposes. Governments can also continue to improve and enforce hunting, trade, and environmental regulations that protect endangered species. Lawmakers also play a role in land management and development practices that work to protect wildlife and preserve open spaces.

Sea Turtle Release

NOAA/NMFS/Pacific Islands Fisheries Science Center Blog

Sea Turtle Release

In the long term, we need to curb pollution, promote sustainable development, and slow the rate of climate change and mitigate its impacts to give terrestrial and marine life a chance to adapt. We can prevent future extinctions and help create a better future for the planet.